Questions for Peter Laidler about bore Erosion

[Alfred]

First some clarification needed.
The following quoted posting attributed to Peter Laidler has been quoted numerous times recently to supposedly prove that Cordite erosion can not produce an unsafe bore.

Right, here goes, now that we've got a bit more meat on the bone. I have to tell you that I'm not a chemist and my physics is limited to Uni level mechanical engineering. But I MUST stress here, that the break-up of No4 barrels in Cadet service was played up out of all proportion. EVERY single weapon in the British Army is examined AT LEAST once every year by the unit Armourers and if the unit doesn't have a unit Armourer, such at Cadet Forces and outlying TA units etc etc, then a what we call P.R.E. team travel out and examine them. They have a Landrover or a van and all the gauges. The PRE armourer is usually a time served ex apprentice and retired so he is on top of his game.

He ascertains the mechanical status of the weapons and if it's unserviceable, then it's called in and scrapped. It's as simple as that! There is NO SUCH THING as a dangerous weapon being left '....just because it's for the Territorials or Cadets' It simply CANNOT happen......., never, not even in 20 years (But someone out there will know better, I can feel the flak coming in already. Helmets on lads!) If it is left, awaiting call in to workshop or Ordnance, it will be clearly labelled with a special form called an AFG 1045, a workshop call-in form ..... or something like that! But obviously, the unserviceable DP rifles will remain.............

Of the two rifles that hit the headlines, the spectacular one, when a Cadet lost a couple of fingers. Let me tell you about that one. At the time, the RAF still retained their own Ordnance system for Cadets and this rifle was a DP rifle. The RAF method of DP'ing was to bore a xxxxing big 3/8" hole down, through the top handguard, through the barrel and through the fore-end and had the letters DP stamped in equally xxxxing big letters all over the rifle. However, they weren't marked with white bands like the Army versions. Anyway a Cadet, under supervision (?) on a range, fired this rifle and naturally, it didn't go bang because the bolt was welded up and the striker was short. So the supervisor, put another bolt in and this time it DID go bang ....., in a big way which took a couple of fingers off.

It was said that he looked at the fore-end when the rifle was in the rack but there was no hole visible. They didn't find sufficient wood after it blew to state with any certainty that it DID have a xxxxing big hole. Mind you, it certainly DID have a xxxxing big hole after the event!

It was nothing to do with the rifle at all and the Board of Enquiry stated this in clear terms.

The next one was another Cadet firing a service rifle on a range without a bolt head. The rifle was hand loaded and fired. The bolt blew and tore off the bottom locking lug but the top lug remained intact. Injuries to face and eyes but nothing lasting. Once again, the cause was obvious. Lack of adult supervision.

We all thought these incidents were a bit coincidental with the fact that certain manufacturers were pushing for their rifles to be taken into service so these little incidents were blown out of all proportion. I have to say that the all-clear was given and to my knowledge, Cadets were still firing .303" rifles with RG55, RL52 and HXP ammo until they got their SA80 rifles in 1988-89 or so.

How do I know this, well until about then, I used to get a call from the training teams (where are you now S/Sgt Cox and Larhu)a week or so before range days and examine 12 or so rifles and Brens as a 'double check' and take my own .303 down so as to make good use of the kind ammo facility laid on!

As for the crazing problems, well, while there was crazing, and I saw some, we used a bore-scope and if 'in the opinion of the examining armourer' it was excessive, the rifle was scrapped. But I never saw a service rifle that exploded because of it! We did have a very good example of it for illustration purposes and a few cut-away barrels at Shrivenham.

The above is I suppose is a reaction to the following.

(from AR, DB Miscellany, Nov88, p65)
The following warning came to us from the United Kingdom Liason Office,
Armament Research, Development and Engineering Center, Picatenny
Arsenal, N.J.
"1. In July 1987 a UK MOD ban was placed on the firing of ball rounds
from .303 (cal.) No. 4 rifles in UK service as a result of two
explosions which occurred in the chamber area of the weapons and
resulted in burst barrels.
"2. UK MOD investigations found that the barrel explosions were as a
result of severe 'craze cracking' of the two barrels which were of
indeterminate age and life.
"3. UK MOD have initiated a study into why some barrels suffer craze
cracking and others do not, but results of this are not expected to be
complete for some time, and even then might not be conclusive.
"4. Because, in peace-time, .303 No. 4 rifles are only used in Cadet
units, it has been decided that it is not cost-effective to carry out
detailed examinations of all barrels, particularly as the cadets are
being issued with the new L98A1 Cadet GP Rifle. The firing ban will
therefore remain in force.
"5. Users of the No. 4 rifle worldwide, whether civilian or military,
are strongly advised to have the weapons closely examined for signs of
craze cracking and condemned accordingly. Thereafter, it is recommended
that any barrels which have passed such inspection should be examined
regularly for such signs and condemned if necessary."
Owners of the .303 No. 4 rifles should certainly heed the advice in the
UK safety notice to have them "closely examined" before firing them
again. The examination should be conducted, preferably, with the aid of
a good optical bore-scope, by an experienced gunsmith who is familiar
with the signs of erosion in gun barrels. If there are any signs of
roughness from erosion in the barrel immediately ahead of the chamber,
or any other visible defects in the barrel or chamber walls, then the
barrel should be regarded as suspect and the rifle *should not be fired*
until it has been properly fitted with a new barrel.

I of course don't have every article I've read instantly at hand to post as an appeal to authority so the only way I can discuss this will be on the basis of published scientific fact and investigations of erosion problems with Cordite ammunition.

First off I have a few questions about your experiance in examining heavily eroded bores.
Sources I'd studied many years ago, including expert testimony in a criminal negligence wrongful death suit, experiments by Hiram Maxim, studies of erosion patterns and craze cracking in Naval gun tubes, arguments in parliment over the effects of cordite on rifle and machinegun bores,etc coupled with personal examination of badly eroded Enfield rifle bores of rifles that made it into circulation here after decades of hard use beyond the control of the British military all lead to some basic conclusions.

1. Cordite propellant as used in .303 ammunition was and remained highly erosive due to high operating temperatures and the chemical make up of its products of combustion, notably Oxides of Nitrogen that degrade into Nitric Acid.
Reduction of the Nitroglycerine content of Cordite MD made it much less erosive and chemically erosive (as opposed to corrosive) than Cordite Mk 1 ,but as Hiram Maxim had said of dangers of degradation and sweating nitro at temperatures over 125 degrees, it was a matter of quantity rather than qualities.

2. As you'd noted craze cracking is a recognized factor, which if found to be significant in inspection of a bore would normally result in that barrel being condemned.

From what I've dug up so far and what I remember from earlier studies.
Craze cracking develops quickly, often with the first rounds fired, gas cutting and chemical erosion can deepen and undercut cracks resulting in either a loss of barrel metal in a more or less uniform manner or a relatively large chunk breaking free to obstruct a projectile.

3. Due to the Lee based Enfield actions' separate bolt head and little enclosure by the receiver ring, excessive pressures are more likely to cause a blow out of a cartridge head or failure of the bolt head than a burst barrel or receiver ring as a Mauser like design would suffer. In this respect a perceived weakness of design becomes a fortuitous benefit in a case of excessive pressures.
Early tests seem to indicate that Enfield barrels are more likely to snap off than split when the cause of excess pressures is a bore obstruction.

4. If gas erosion is in the form of "Washing" the grooves and lands can erode at much the same rate, as opposed to mechanical erosion where lands wear much faster than grooves. I've seen this recently in a BSA 1912 barrel, the grooves appearing very deep and the lands very rounded, the bore at that point grossly over sized.
This phenomena can make it less easy to spot the extent of erosion, or identify low spots and freebore. A Star Gauge would spot it but looking from either end of the barrel it wouldn't be obvious to one who didn't know what to look for.

3. The testimony in the negligence case I mentioned (as near as I can remember a case I read about around 40+ years ago, said the bore of the rifle in question showed a distinctive pattern of erosion. The bore from about three inches past the throat was increasingly over sized for several inches, more so than the throat itself, then narrowed gently till a point about fourteen or more inches up the bore where it returned to more or less normal diameter.
Near as I can tell this pattern roughly coincides with the erosion pattern reported by Hiram Maxim in testing machinegun barrels, though in those tests the damage was more locallized in an "egg shaped chamber" several inches past the leade, probably he was using cordite Mk 1.
From studying the sealants used it appears that if the resins fron Swedish Pitch and asphaltum, mixed with atomised lead, were allowed to build up they partly protected the bore but the length of bore protected and extent of protectin varied greatly according to average number of rounds fired between cleanings and how well the bore was cleaned.
I've seen this coating extend far down the bore. There seems to be a hot spot in the propellant burning and pressure curve that results in increasingly rough surface about 14 inches up the bore of heavily fouled barrels.

The witness testified that the first bullet fired that day had been heated by blowby gases in the oversized portion of the bore, then encountered a roughened section further up, the bullet shed its jacket and the core blew through, leaving most of the jacket stuck tightly in the bore. The victim didn't recognize the danger and fired a second time. The bullet telescoped into the shed jacket and resulting pressures caused the bolt head to fracture, part of the bolt head and extractor entering the victims body and slicing a large vein, he probably died of shock as much as loss of blood, but the injury would have been fatal without prompt surgery regardless.

4.
Again I'm going only by memory, but I recall a letter to a magazine which described the destruction of two No.4 rifles by barrel failure due to craze cracking. As I remember it the rifles had round counts of aproximately 125,000 rounds and 80,000 rounds.

Had I known that some would mis-construe your comments as a claim that there has never been a recorded case of barrel failure due to cordite erosion I'd have carefully put those articles away for future reference, the magazines may still be here I just wouldn't know where to look for them at the moment.

I had intended to obtain some Cordite loaded Mk VII ammunition to use in my 1915 No.1 Mk III, till I began looking into the subject more closely after seeing your comments mis-used.
The bore of my 1915 is in very nice condition with little or no wear and certainly no visible erosion, even on close inspection, the bore mikes exactly .303 with .311 groove to groove.
There are many reasons not to use Cordite in a bore that has seen little if any cordite over the years. The main one being that even in a best case scenario Cordite erosion of the throat limits the type of bullets that the bore can handle with acceptable accuracy.

Second hand quotes from "Sniping in France" indicate that long range accuracy of WW1 sniper rifles was adversely effected by no more than the first 500 rounds of Cordite loaded Mk VII ammunition.
Arguments in Parliment and Hiram Maxim's test results indicated that a heavy machinegun bore would be eroded to the point that effective long range accuracy was ruined by the first 3,000 rounds of cordite loaded ammunition.
Later improvements seem to have extended useful accuracy life to around 10,000 rounds of Mk VII ammunition.
I've seen Vickers barrels quoted as having a useful life of 10,000 rounds when the Mk VII load is given as ammunition type, and other more vague cites of 18,000 rounds but this may have been with Mk VIIIZ.

I would like to know if there was a estimated barrel life for the No.1 and No. 4 rifles when cordite was used compared to when Nitro Cellulose propellants were used. Some Non Cordite US manufactured .303 Ball of WW2 used double base propellants not much if any less erosive than cordite.

Take your time in answering. I'm sure you have better resources for looking up recorded cases of barrel failures than I do.


Edited to add

These barrel and action failures involved No.1 Rifles I would expect, though as usual little detailed information is available as to the exact model, possibly earlier types of Long Lee enfield or even Lee Metfords, and ultimate cause of the accidents. No information on round counts or how long those rifles had been in service.

The Gentleman speaking here does make a good point about word of failures of Enfield Rifles not getting much if any play even in those days when they were a major issue military rifle.

Sir .FREDERICK BORDEN. Recently, and the report is most satisfactory from the point of view of the military experts here. They found the same defects which had been discovered here, though not all of them, and all the defects which they discovered had been remedied before this report reached us. Now, I do not wish to say a single word against the Lee-Enfield rifle ; but. in justice to the Ross rifle and to Sir Charles Ross, I think it is only fair for me to point out that since these defects were heralded abroad to the injury of the Ross rifle and for the purpose of criticising the department in some cases, I had an inquiry made as to the Lee-Enfleld rifle. Nobody had ever before heard a word about any defect in that rifle; and yet I have a list here of cases that have happened within the last two years, and I will read some of them:

Barrel burst, one bullet telescoping, another remaining in barrel.

Barrel bulged; obstruction in barrel (two rifles).

Breech burst, either defective bullet or breech not properly closed.

Barrel bulged, endeavouring to blow out pull-through.

Muzzle of rifle expanded.

Rifle burst, probably due to defective bullet jamming in barrel and second shot being fired.

Rifle burst.

Rifle burst. Proceedings of board forwarded.

Barrel burst, detective cartridge.

Barrel burst, due to rifleite cartridge being fired.

Barrel burst, defective cartridge, In two cases.

Striker damaged.

Barrel bulged, bullet telescoped.

Barrel bulged, obstruction in barrel.

Spread barrel near muzzle.

Broken bolt.

Broken bolt, barrel twisted and piece blown out near breech.

Bolt broken and bulge in barrel near breech.

Breech bolt broken and kink in barrel.

Breech bolt broken.

Cocking piece broken.

Breech bolt broken.

Rifle barrel burst at side.

In all the tests of the Ross rifle there has never been a case of a burst barrel.

Mr. BERGERON. What do they use in the Mounted Police?

Sir FREDERICK BORDEN. I think they use the Winchester. I say that during the last year far more defects have been shown in the Lee-Enfield rifle, which has been the service rifle in England as well as in Canada, than have been found In the Ross rifle. I mention this merely to show the House that the discovery of defects in individual rifles of the Lee-Enfield class is a matter of every day occurrence.

Mr. FOSTER. Where did these defects develop?

Sir FREDERICK BORDEN. At the annual shooting, at different places in our


own country, and in rifles which have been regularly issued to the militia. I asked for n report from the quartermaster general in order that I might know whether there was anything like an absolutely perfect rifle.

Mr. DANIEL. What ammunition was used in these rifles?

Sir FREDERICK BORDEN. The same In both—that manufactured at Quebec, which is precisely the same as the service ammunition in England. I merely mention that incidentally, in justice to the Ross Rifle Company and to myself. Now, I do not wish to detain the House, because I assume that this matter will be discussed later on. when there will be much better opportunities of discussing it intelligently after the papers have been brought down. Although the papers moved for are most voluminous, 1 will endeavour to have the return prepared and brought down, so that when the militia estimates out of which these rifles are paid for are reached, we shall be better prepared to discuss the matter than we are to-day, and when my hon. friends will be better prepared to criticise intelligently than they can possibly be today, when they must necessarily base their criticisms largely on rumours published in the newspapers and circulated throughout the country.

http://books.google.com/books/pdf/De...j-gaOz7NVMPOAg

Information

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[smelly sam]

First some clarification needed.
The following quoted posting attributed to Peter Laidler has been quoted numerous times recently to supposedly prove that Cordite erosion can not produce an unsafe bore....


------

If I am reading this correctly the claim is that Cordite cannot make a good barrel, unsafe.

Mmmmm....

Put enough rounds through (of Cordite) and the barrel must deteriorate due to the combination of chemical attack, heat stress, friction and 19 ton or so of pressure - each and every time it goes bang.

Barrel life is an inverse function of proper cleaning and the crud being fed down it.

Feed the rifle crud ammo + don't clean = problems.

According to an authority on the subject, the "Musketry Regulations, Part 1 of 1909 (Amended 1912)" states...

Pg 31, Item 85

"When care is used in cleaning, 5.000 to 6,000 rounds can be fired from a rifle befors it becomes unserviceable."

This is in the section dealing with 'Care of Arms' where much emphasis is given to the damaging use of the wire gauze and pull-through.

No where have I (yet) seen a muzzle protector fitting like those for earlier marks, which would have negated the cord rubbing against the crown.

Best advice ever received from an old timer was,

"If the rifle is older than you, then slug out BOTH ends of the barrel, then measure the slugs carefully".


Hope this helps a bit.

Selly Sam

[Alfred]

First some clarification needed.
The following quoted posting attributed to Peter Laidler has been quoted numerous times recently to supposedly prove that Cordite erosion can not produce an unsafe bore....


------

If I am reading this correctly the claim is that Cordite cannot make a good barrel, unsafe.

Mmmmm....

Put enough rounds through (of Cordite) and the barrel must deteriorate due to the combination of chemical attack, heat stress, friction and 19 ton or so of pressure - each and every time it goes bang.

Barrel life is an inverse function of proper cleaning and the crud being fed down it.

Feed the rifle crud ammo + don't clean = problems.

According to an authority on the subject, the "Musketry Regulations, Part 1 of 1909 (Amended 1912)" states...

Pg 31, Item 85

"When care is used in cleaning, 5.000 to 6,000 rounds can be fired from a rifle befors it becomes unserviceable."

This is in the section dealing with 'Care of Arms' where much emphasis is given to the damaging use of the wire gauze and pull-through.

No where have I (yet) seen a muzzle protector fitting like those for earlier marks, which would have negated the cord rubbing against the crown.

Best advice ever received from an old timer was,

"If the rifle is older than you, then slug out BOTH ends of the barrel, then measure the slugs carefully".


Hope this helps a bit.

Selly Sam

It certainly helps some.
I'd run across the 6,000 rounds till unserviceable reference before, but my guess is this was when Mk I Cordite with its higher Nitroglycerin content was still in use.
Earlier references to use of Cordite in the Lee Metford say that barrel life of 10,000 rounds when using the Black Powder loads was cut to 4,000 when using Cordite, almost certainly Mk I cordite at that time, which resulted in the changeover to Enfield type rifling for all later Enfield .303 rifles. It was then claimed that the bore life of 10,000 rounds was restored when Enfield type rifling was used.
Whether the expectations of servicable accuracy were different or longer barrels of the earlier models of Enfield allowed more useful accuracy than the slimmer and shorter barrels of the SMLE is hard to say.

I'd really like to confirm some information which at this point I can only dedge up from memory. At the time I did most of my reading on the subject I had only an academic interest in the Enfield Rifles, but now I own and shoot them and have put a number of these old rifles back into decent firing condition for friends.
On a couple of occasions I've had to tell Enfield owners that their rifle's bore looked to be unsafe, despite good outward appearances.

The testimony in a negligence case involving death caused by severe Corditie Erosion of an Enfield barrel was always at the back of my mind when examing these old rifles, so I knew what to look for.

A fairly new factor has to be considered as well. Many rifles long retired to wall hanger status are now coming onto the market, and young shooters who have little experiance with anything other than modern ammunition may not know what to look for.

The unusual erosion pattern of a bore that had been subjected to thousands of rounds of cordite of unknown vintage under the worst conditions of battle in far away climes may not show as noticably in a rifle that saw little but infrequent range use with the best quality ammunition and that with careful cleaning after relatively few rounds had been fired.
Two rifles of exactly the same age and round count might be worlds apart in the condition of the bore and the pattern of wear.

I've run across references to some older Enfields not considered suitable for Mk VII ammunition being lapped out for the last 1/3 of the bore to allow reasonably safe use of the issue ammo. I'd always wondered why they lapped only the final 1/3 of travel.
I'm thinking that a bore that showed increased bore size from the throat to that point due to gas washing would exhibit a pressure spike when the bullet encountered the less worn last 1/3 of travel. Lapping this section of bore would serve to prevent this sort of spike, as well as to remove the worst of the gas pitting caused by oscilation of the gases at the point where the pressure curve maxed out.

The resin treated sealants used in .303 case necks has an ablative heat shielding property.
I can remember test results of cartridges fired with and without the sealant. If no sealant was used the bore wore out at the throat about three times as fast, with usable accuracy reduced to 1500-2000 rounds.
These tests were run in a manner that corrosion from mercuric primers wouldn't have had time to take its toll, so gas erosion and mechanical wear were the only factors.
Cupro-nickel jacket materials would have been a wild card, since jacket materials were not mentioned in those tests.

I've tried to find those books and magazines with articles on tests like these. I probably still have them here somewhere but I have thousands of hardback books on every thing from anthropology, and theology to Walt Disney here, with few of them in order, and thousands of magazines to sort through.
So I'm pretty much limited to searching the net for Googlebooks and the like.
I have found a number of very interesting books writen immediately pre and post WW2 with some of the information I need, luckily in public domain.

Finding specifics of barrel and action failures is supprisingly difficult, even in recent cases.
One fellow posts about losing part of his thumb when his WW1 Enfield blew up on him, but gives no useful information on the incident, another warns of some European Mark VIIIZ ammunition blowing out the extractor of a well worn No.4 rifle but not damaging a No.4 rifle in better condition. His concern being the ammunition rather than the rifle that couldn't handle it and exactly why.
A recent incident involving the death of a respected collector when firing a very different rifle, but one whose ammunition while in service was known to erode bores in much the same manner as cordite, seems to have not been investigated at al.
I expect that any such investigation would involve insurance companies and the family would not want the incident dedged up on forums and such. We may never know whether excessive erosion was the ultimate cause of that accident, but all signs point to it.

When American rifles failed in testing the incidents were far from secret, confidence in weapons is a very important consideration in our military. Causes were investigated throughly and private sector manufacturers called on for input, the problems discovered and dealt with.

As the notes from the Ross rifle controversy show burst barrels of Enfields got almost no public attention. Probably in part because these incidents seldom caused death or serious injury.
The more open action of the Lee-Enfield design vents gases away swiftly and seldom results in shattered receiver rings with heavy shrapnel like a burst Springfield or Mauser action might when gases were trapped in the covered locking recesses of the rear of the rings.

I've run across cites claiming a barrel life of 30,000 to 50,000 rounds for the FN-FAL in British service. The article had Major Reynolds as a contributor, and the major factor in this increased bore life compared with the Enfield was given as the switch from Cordite .303 of the No.4 to the 7.62 NATO loaded with single base Neonite powders of the FAL rifles.
I'm supposing that the 30,000 round figure is for frequent rapid fire under combat conditions and the 50,000 round figure for slow fire under the best conditions.

"If the rifle is older than you, then slug out BOTH ends of the barrel, then measure the slugs carefully".

Heres where unequal erosion as reported in the negligence cases comes into play.
If the bore has significant erosion several inches beyond the throat the bore might appear to be within limits at either end but still be dangerous, due to unexpected freebore travel and gas washing of the bullet jacket causing failure of the jacket with cores blown out and jacket materials left behind as bore obstructions. This fits in with the comments on burst Enfield barrels during the Ross Rifle debates.

[Peter Laidler]

This subject is presently being aired on the Jouster Lee Enfield forum but in simpler form, by cutting out the irrelevant crap. I stand by exactly what I said in my earlier article. In my limited experience of No4's and 5's as an Armourer since the very early 60's, I only ever encountered two accidents that involved serious injury with them. And these two accidents were thorougly investigate and a Board of Enquiry was held.

For a No1 rifle, if the .308" plug gauge enters into the leed by more that 1/4" then the barrel WILL be rejected
For a No4 and 5 rifle, if the .310" dia plug gauge enters into the leed by more than 1/4", the barrel WILL be rejected.

In Armourers language, 'rejected' simply means scrapped, chopped, the big scrapyard in the sky, the gas axe. It will never fire another round again.

From the metallurgical point of view, there is not the remotest possibility that a rifle that rejects the .308 or .310 gauge as detailed above will break while using military ball ammo. (Oh doubters ...., get real!) And in any case, the enquiry for the rifles I mention, subject to the accidents, BOTH were within the Armourers examination criteria............., yes, even the RAF one with the 3/8" hole through the barrel 4" ahead of the breech end, that blew at the weak point.

How do I know this, well, just to satisfy myself, I have just confirmed it with the very Armourer who examined the 'no bolt head rifle'.

The guiding light MUST be to this. Don't worry about it. If your rifle has a sound chamber and the leed rejects the .308 (or .310) plug gauge, then just enjoy it and carry on

[Amatikulu]

As the individual who first asked the question of Peter Laidler quoted by Alfred at the beginning of this thread, I'd like to clarify that Peter's response which I quoted, was never used to "prove that cordite erosion can never produce an unsafe bore." The quote was used in response to statements by a person known as Gun Nut (that writes just like Alfred), that I wanted to verify as they were largely contrary to my understanding - here is the thread where it all began:

Yesterday's Weapons Forums • View topic - I've Succumbed To The Urge

And here is the original thread on Jouster

http://www.jouster.com/cgi-bin/lee-e....pl?read=69538

Reading these will give those interested a greater understanding of this topic.

[Alfred]

This subject is presently being aired on the Jouster Lee Enfield forum but in simpler form, by cutting out the irrelevant crap. I stand by exactly what I said in my earlier article. In my limited experience of No4's and 5's as an Armourer since the very early 60's,

Not having read your biography and only having read the comments of others who quoted your post I had the impression that you'd had much more experiance with the No.4 rifles while they were still in service, and might know about any recorded instances of barrel failures.

I only ever encountered two accidents that involved serious injury with them. And these two accidents were thorougly investigate and a Board of Enquiry was held.

Were you still an armorer in 1987?

For a No1 rifle, if the .308" plug gauge enters into the leed by more that 1/4" then the barrel WILL be rejected
For a No4 and 5 rifle, if the .310" dia plug gauge enters into the leed by more than 1/4", the barrel WILL be rejected.

Neither of which would reveal any erosion beyond that point. If the pattern of erosion mentioned by Hiram Maxim held true the bore could be of larger diameter several inches past the throat than at the throat itself.

In Armourers language, 'rejected' simply means scrapped, chopped, the big scrapyard in the sky, the gas axe. It will never fire another round again.

From the metallurgical point of view, there is not the remotest possibility that a rifle that rejects the .308 or .310 gauge as detailed above will break while using military ball ammo. (Oh doubters ...., get real!) And in any case, the enquiry for the rifles I mention, subject to the accidents, BOTH were within the Armourers examination criteria............., yes, even the RAF one with the 3/8" hole through the barrel 4" ahead of the breech end, that blew at the weak point.

How do I know this, well, just to satisfy myself, I have just confirmed it with the very Armourer who examined the 'no bolt head rifle'.

Neither incident you speak of was mentioned in the MOD warning sent to the Picatiny Arsenal. I'd read of two burst No.4 rifles sometime after that warning was sent to the Armerican Rifleman, which is the journal of our National Rifle association. Those rifles burst because sections of bore broke free and swung down forming bore obstructions, no mention was made of injuries in those particular incidents.
I'd hoped you had better information on these two incidents.

The guiding light MUST be to this. Don't worry about it. If your rifle has a sound chamber and the leed rejects the .308 (or .310) plug gauge, then just enjoy it and carry on

Now here is the quandry, I've seen the erosion pattern I spoke of with my own eyes, the bore opened up in diameter several inches further down the bore and remaining larger than the diameter at the throat for several inches.
One older Lithgow I examined had a chunk of one land missing about fourteen inches up the bore, at exactly the spot mentioned in the testimony I spoke of.
Its unlikely that the Enfield Rifles that burst in Canada had not been examined by the same criteria you've spoken of, though of course anything is possible, and standards of inspection may have been slack at times.

The appearance of those bores was like an elongated internal bulge with no outward sign of a bulge.

At the very least a heavily used barrel should be inspected carefully with a bore scope whether it passes the gauge test or not, and if a star guage of some kind were available that would be a plus.
The plug gauges you speak of cannot indicate the amount of gas erosion of the grooves only the erosion of the lands at throat and muzzle.
Gas washed rifling can be eroded near equally in the grooves as well as the lands giving grossly oversized sections of bore.

Among my references here I have a bundle of pages a gunsmith photo copied for me many years ago on rebarrling the Mauser rifles, one section details the sort of bore defects one should look for and there are a number of photos of blown up actions with a detailed study on just why these actions failed. I've found no mention of any similar studies on Enfield rifles that have failed in otherwise normal use.

I've tried to find out more about this subject at several forums. I use a different username on each of these forums, never saw any harm in that.
I've never visited the Jouster forum except to look in on a linked post by yourself.
I was unaware that the subject had been re-opened at Jouster.

I was not speaking of any posting by Amatiklu, others on another board have gone overboard with accusations of my defaming both you and the Enfield rifle, the British Military, etc in the most childish terms.
I'm looking for facts. Study of previous accidents goes a long way towards preventing future accidents.


If you would like to see some of the outrageous claims made using your post as an appeal to authority I can PM you a link to that thread.
I was not in a very good mood at the time and with the specious and often false claims of the opposition on that thread I didn't have much success in either finding out what I needed to know or impressing on anyone the need to properly inspect a rifle bore. Looking down either end or gauging either end is just not enough, it isn't for any other rifle in existence so I can't see the Enfield being immune to the same forces that are at work on every other rifle.

There is a lot more information available on erosion patterns of various propellant types on Artillery barrels. Mid bore erosion is a recognized phenomena most noticable when double base propellants are used. Cordite MD has nearly three times the Nitroglycerin content that modern double base powders use, so one would naturally expect the symptoms to be magnified in barrels subjected to tens of thousands of rounds of Mk VII SAA.


While I might agree that reaction to the MOD warning might have been overblown, I simply do not believe that the MOD somehow confused the two incidents you describe with bursts caused by gas erosion acting on craze cracked bores, and then went so far as too send a warning to our Picatiny Arsenal about a non existent safety concern.

I was told that if I had any questions about your post I should ask you about it, I'm doing just that.
I have to say that that Smellie Sam's post provided much more useful information.

Theres very little to be found on the subject in recent publications, but a fair ammount to be found in public domain PDF files of studies on rifles and ammunition done before WW2.
If no other sources are available I'll just have to muddle through with those for now.

[Alfred]

[QUOTE=Alfred;17971]Not having read your biography and only having read the comments of others who quoted your post I had the impression that you'd had much more experiance with the No.4 rifles while they were still in service, and might know about any recorded instances of barrel failures.



Were you still an armorer in 1987?



Neither of which would reveal any erosion beyond that point. If the pattern of erosion mentioned by Hiram Maxim held true the bore could be of larger diameter several inches past the throat than at the throat itself.


Neither incident you speak of was mentioned in the MOD warning sent to the Picatiny Arsenal. I'd read of two burst No.4 rifles sometime after that warning was sent to the Armerican Rifleman, which is the journal of our National Rifle association. Those rifles burst because sections of bore broke free and swung down forming bore obstructions, no mention was made of injuries in those particular incidents.
I'd hoped you had better information on these two incidents.



Now here is the quandry, I've seen the erosion pattern I spoke of with my own eyes, the bore opened up in diameter several inches further down the bore and remaining larger than the diameter at the throat for several inches.
One older Lithgow I examined had a chunk of one land missing about fourteen inches up the bore, at exactly the spot mentioned in the testimony I spoke of.
Its unlikely that the Enfield Rifles that burst in Canada had not been examined by the same criteria you've spoken of, though of course anything is possible, and standards of inspection may have been slack at times.

The appearance of those bores was like an elongated internal bulge with no outward sign of a bulge.

At the very least a heavily used barrel should be inspected carefully with a bore scope whether it passes the gauge test or not, and if a star guage of some kind were available that would be a plus.
The plug gauges you speak of cannot indicate the amount of gas erosion of the grooves only the erosion of the lands at throat and muzzle.
Gas washed rifling can be eroded near equally in the grooves as well as the lands giving grossly oversized sections of bore.

Among my references here I have a bundle of pages a gunsmith photo copied for me many years ago on rebarrling the Mauser rifles, one section details the sort of bore defects one should look for and there are a number of photos of blown up actions with a detailed study on just why these actions failed. I've found no mention of any similar studies on Enfield rifles that have failed in otherwise normal use.

I've tried to find out more about this subject at several forums. I use a different username on each of these forums, never saw any harm in that.
I've never visited the Jouster forum except to look in on a linked post by yourself.
I was unaware that the subject had been re-opened at Jouster.

I was not speaking of any posting by Amatiklu, others on another board have gone overboard with accusations of my defaming both you and the Enfield rifle, the British Military, etc in the most childish terms.
I'm looking for facts. Study of previous accidents goes a long way towards preventing future accidents.


If you would like to see some of the outrageous claims made using your post as an appeal to authority I can PM you a link to that thread.
I was not in a very good mood at the time and with the specious and often false claims of the opposition on that thread I didn't have much success in either finding out what I needed to know or impressing on anyone the need to properly inspect a rifle bore. Looking down either end or gauging either end is just not enough, it isn't for any other rifle in existence so I can't see the Enfield being immune to the same forces that are at work on every other rifle.

There is a lot more information available on erosion patterns of various propellant types on Artillery barrels. Mid bore erosion is a recognized phenomena most noticable when double base propellants are used. Cordite MD has nearly three times the Nitroglycerin content that modern double base powders use, so one would naturally expect the symptoms to be magnified in barrels subjected to tens of thousands of rounds of Mk VII SAA.


While I might agree that reaction to the MOD warning might have been overblown, I simply do not believe that the MOD somehow confused the two incidents you describe with bursts caused by gas erosion acting on craze cracked bores, and then went so far as too send a warning to our Picatiny Arsenal about a non existent safety concern.

I was told that if I had any questions about your post I should ask you about it, I'm doing just that.
I have to say that that Smellie Sam's post provided much more useful information.

Theres very little to be found on the subject in recent publications, but a fair amount to be found in public domain PDF files of studies on rifles and ammunition done before WW2.
If no other sources are available I'll just have to muddle through with those for now.


I've found a few sources of information on the higher operating temperatures of Cordite propellants.

Now, it is admitted that the erosion of equally proportioned guns is, for similar velocities, dependent on some function of the caliber, and, further, that in guns of any particular caliber it depends on the weight of charge. At first sight it might therefore be argued that the smaller charge of large- sized powder would be the best; but consulting Sir Andrew Noble's researches —see Vol. ccvi., Phil. Trans., Royal Soc.—the following table has been compiled showing for various explosives certain calorific data by which the ballistic energy and the erosive quality of dillerent types of powder may be directly compared:—

i Density of charge in a

closed vessel 0.10 .20 .30 .10 .50

Volume of (ins per Gramme of E.rnlosive

Cordite Mark 1 878.5 875.5 848.0 820.0 798.3

Cordite M.D 918.0 913.5 873.0 832.0 789.5

Nitro-cellulose 980.0 931.0 88.3.0 811.0 802.0

Units of Heal per Gramme

Cordite Mark 1 1174.0 1170.5 1186.5 1223.4 1287.0

Cordite M.D 959.0 061.5 1008.0 1090.0 1178.0

Nitro-cellulose. 818.0 850.5 900.5 951.5 1015.0


Temperature of Explosive " C"

Deg. Deg. Deg. Deg. Deg.

Cordite Mark 1 3100 3760 4435 4960 5270

Cordite M.D 2565 3240 3901 4551 5051

Nitro-cellulose 2415 2815 3335 3832 4212

It will be observed that with Cordite Mark I, which contains the largest percentage of nitro-glycerin, the gas volume produced is the smallest, while the units of heat are greatest; further, that as the proportion of nitro-glycerin in a powder is reduced, the gas volume increases and the units of heat decrease.

http://books.google.com/books/pdf/Jo...meuPeeJPAGXb8Q

[Alfred]

[QUOTE=Alfred;17974]

Not having read your biography and only having read the comments of others who quoted your post I had the impression that you'd had much more experiance with the No.4 rifles while they were still in service, and might know about any recorded instances of barrel failures.



Were you still an armorer in 1987?



Neither of which would reveal any erosion beyond that point. If the pattern of erosion mentioned by Hiram Maxim held true the bore could be of larger diameter several inches past the throat than at the throat itself.


Neither incident you speak of was mentioned in the MOD warning sent to the Picatiny Arsenal. I'd read of two burst No.4 rifles sometime after that warning was sent to the Armerican Rifleman, which is the journal of our National Rifle association. Those rifles burst because sections of bore broke free and swung down forming bore obstructions, no mention was made of injuries in those particular incidents.
I'd hoped you had better information on these two incidents.



Now here is the quandry, I've seen the erosion pattern I spoke of with my own eyes, the bore opened up in diameter several inches further down the bore and remaining larger than the diameter at the throat for several inches.
One older Lithgow I examined had a chunk of one land missing about fourteen inches up the bore, at exactly the spot mentioned in the testimony I spoke of.
Its unlikely that the Enfield Rifles that burst in Canada had not been examined by the same criteria you've spoken of, though of course anything is possible, and standards of inspection may have been slack at times.

The appearance of those bores was like an elongated internal bulge with no outward sign of a bulge.

At the very least a heavily used barrel should be inspected carefully with a bore scope whether it passes the gauge test or not, and if a star guage of some kind were available that would be a plus.
The plug gauges you speak of cannot indicate the amount of gas erosion of the grooves only the erosion of the lands at throat and muzzle.
Gas washed rifling can be eroded near equally in the grooves as well as the lands giving grossly oversized sections of bore.

Among my references here I have a bundle of pages a gunsmith photo copied for me many years ago on rebarrling the Mauser rifles, one section details the sort of bore defects one should look for and there are a number of photos of blown up actions with a detailed study on just why these actions failed. I've found no mention of any similar studies on Enfield rifles that have failed in otherwise normal use.

I've tried to find out more about this subject at several forums. I use a different username on each of these forums, never saw any harm in that.
I've never visited the Jouster forum except to look in on a linked post by yourself.
I was unaware that the subject had been re-opened at Jouster.

I was not speaking of any posting by Amatiklu, others on another board have gone overboard with accusations of my defaming both you and the Enfield rifle, the British Military, etc in the most childish terms.
I'm looking for facts. Study of previous accidents goes a long way towards preventing future accidents.


If you would like to see some of the outrageous claims made using your post as an appeal to authority I can PM you a link to that thread.
I was not in a very good mood at the time and with the specious and often false claims of the opposition on that thread I didn't have much success in either finding out what I needed to know or impressing on anyone the need to properly inspect a rifle bore. Looking down either end or gauging either end is just not enough, it isn't for any other rifle in existence so I can't see the Enfield being immune to the same forces that are at work on every other rifle.

There is a lot more information available on erosion patterns of various propellant types on Artillery barrels. Mid bore erosion is a recognized phenomena most noticable when double base propellants are used. Cordite MD has nearly three times the Nitroglycerin content that modern double base powders use, so one would naturally expect the symptoms to be magnified in barrels subjected to tens of thousands of rounds of Mk VII SAA.


While I might agree that reaction to the MOD warning might have been overblown, I simply do not believe that the MOD somehow confused the two incidents you describe with bursts caused by gas erosion acting on craze cracked bores, and then went so far as too send a warning to our Picatiny Arsenal about a non existent safety concern.

I was told that if I had any questions about your post I should ask you about it, I'm doing just that.
I have to say that that Smellie Sam's post provided much more useful information.

Theres very little to be found on the subject in recent publications, but a fair amount to be found in public domain PDF files of studies on rifles and ammunition done before WW2.
If no other sources are available I'll just have to muddle through with those for now.


I've found a few sources of information on the higher operating temperatures of Cordite propellants.



http://books.google.com/books/pdf/Jo...meuPeeJPAGXb8Q

this book
http://books.google.com/books/pdf/Th..._Hpzgjp9cAZSuw

Gives some excellent information on use of Cordite with both Metford and Enfield rifling.
From the date it was writen it would be most likely Cordite Mk I and the Long Lee rifles that acheived a bore life of 8,000 rounds, rather than 10,000 as I'd at first thought.

Page 92

It will easily be understood that where a very large amount of energy has to be imparted by the powder gases to the bullet in a very short time and on a very small area of base, the destructive effects of the blast of the gases upon the barrel are apt to be very marked. Every time the rifle is fired what is really quite a large blast of white-hot tiame finds its way up the very narrow pipe which the bore presents. Cordite, which has many good qualities (for it keeps in hot and cold climates, is very safe to store and handle, and does not develope higli pressures in the barrel), yet has one grave disadvantage. It is composed of a mixture of two of the most violent explosives known, gun-cotton and nitroglycerine, and the temperature at which it burns is a very high one, higher than the melting-point of steel. It was soon found that the surface of the barrel, where the chamber was narrowed into the rifling, showed signs of damage when only a few rounds of cordite had been fired through it, and that a few hundred rounds were sufficient to effect very obvious injury, and to impair the velocity as well as the accuracy of the shooting.

The peculiar appearance caused by erosion, consisting first of a very minute grooving just in front of the chamber in the direction in which the gases escape up the barrel, and, in a more advanced stage, of an irregular washing away of the surface of the bore, especially at the bottom of the grooves in the breech end of the rifle, and the pitting of the surface, is familiar to all those who take an interest in this subject. On this account it was found advisable to lengthen the ' life ' of the -303 barrel by giving the gases more of the original surface of the bore to eat away, and the deeper five-grooved rifling (p. 00, fig. '27), with the grooves concentric with the bore, and with as much land as there is grooving, was substituted for Mr. Metford's more delicate grooving. At the same time some alterations were made in the loading of the cartridge, which have assisted to diminish the erosive effect, and the ' life' of a barrel when used with cordite now extends to some eight thousand rounds, a matter even more important for machine guns than for rifles. The destructive effect of erosion, while it is common in some degree to all smokeless powders, is much less developed in those which do not contain nitro-glycerine, but no such powder has as yet been produced which has been thought to fulfil the military requirements of this country (which include transport to and from all parts of the world and use in every variety of climate) so well as cordite. The labours of the Explosives Committee, now sitting, may perhaps do something towards solving the problem.

As stated here the erosion in the bottom of the grooves was more pronounced. The bullet itself would offer some protection to the lands, the grooves becoming more and more vulnerable to gas washing due to blowby as erosion progressed.
Whether the "irregular washing away of the surface" meant the difference between material lost in the grooves compared to from the lands, or the loss of more material several inches beyond the throat is hard to say.


The much longer barrel of the pre SMLE Enfield rifles may have contributed to better stabilization of heat damaged bullets once past the danger zone. Greater mass of the barrel and less wood around it would act as a heat sink and allow more rapid radiation of waste heat, than the more enclosed and less massive SMLE barrel.

the '303 with cordite is particularly subject to the effect of erosion, and it has been found necessary to harden the steel barrels inside, the better to withstand its ravages. An excellent demonstration of the effect of erosion is supplied by the Maxim -303 machine-gun. Mr. Maxim stated that the life of a barrel was 3,000 rounds, or, when hardened and tempered inside, about 20,000 rounds. After 8,000 rounds from a soft barrel an enlargement of the bore was noticed just in front of the cartridge chamber ; after 12,000 rounds had been fired it appeared to be scooped out egg-shaped, and the recoil fell off to such an extent that there was not enough energy remaining to work the gun. The velocity of the bullet diminished proportionally.

Page 563
Of the Gun and its development
http://books.google.com/books/pdf/Th...aevoKhE7Bhuxxw
Variations in bore diameter of wartime production rifles would tend to leave some rifles more vulnerable to the effects of erosion.
The Bore of my 1915 rifle is a texbook .303 bore by .311 groove to groove, many others came from the factory with much looser bores and so would show the ill effects of erosion much more quickly.

The odd pattern or erosion that I've seen may not have become visible with the majority of rifles in service use before those barrels were condemned for other reasons after inspections.
Many an Enfield now on the market spent decades in use in third world countries where the closest thing to an armorer was whoever had an old Nagant steel cleaning rod they could use to shove a patch soaked with used motor oil through the bore now and then.
Longbranch No.4 rifles sold to China in the last days of WW2 have begun to show up now and then, who knows what sort of treatment those got.

Spotting the erosion pattern in my Savage No.4 with its two groove bore was easy due to the broad lands. I found it while using a pocket telescope for bore sighting when adjusting the front sight. The telescope doubles as a microscope so I was able to focus on the surface of the lands a fraction of an inch at a time. Using a tightly fitted leather patch on a jag I could feel the variation in diameter from just beyond the throat to about 2/3 the way up the bore. At 14 inches or so the character of erosion pitting changed showing the star shaped cratering caused by oscilating high temperature gases acting like cavitation of a liquid. From that point to the muzzle thin streaks of gilding metal fouling originated at these star shaped pits.
Having more time on my hands than anything else I carefully polished this bore till it was slick and without high spots or low spots, removing perhaps .0005 of the lands or less, bore size now .304 with grooves .314 which is still fairly good for a wartime two groove bore. This also removed chatter marks where a steel rod pushed in from the muzzle had been used for its infrequent cleanings during its last years as a combat rifle in some forgotten pesthole east of the sun and west of the moon.
The rifle is now capable of sub MOA groups to at least three hundred yards using my taylored hand loads so I'm not displeased with the results.
Not much flat ground around here, to shoot at more than three hundred yards it would be from mountain top to mountain top , across a lake which is illegal or down the interstate which is even more illegal.
I now have a place to shoot where I can stretch my legs a bit, at least six hundred yards. I hope to test the No.1 with the PH5A sight there when the new fore end wood gets here.
I had intended to obtain some fairly recent manufacture Mk VII ammunition to test handloads for the rifle using targets fired on with the Mk VII as a control group, but the more I've learned about Cordite the less wise that seems.
This No.1 has managed to last over 90 years without erosion damage so I figure its best to just use Nitrocellulose propellants, or at worst the mildest double base propellants with their bore protecting additives, though apparently these additives still allow more gas erosion than IMR powders.

[Badger]

This thread has been CLOSED by moderator. .......

Well, let me qualify what I'm going to say with the fact that I know for sure I'm just a "country boy" when it comes to Peter's experience, or perhaps even Alfred's, however, I don't know really know anything about him other than his writings here.

To paraphrase and butcher a famous Winston Churchill phrase, "Never has so much been said by so few, to accomplish so little.

To be honest and with all due respect, I can't even follow the facts of this discussion, much less its presentation format. Having said that, it may just be my ignorance on the subject, or pure impatience in wanting to wade through so much "techno-babble" to get to the point.

For those of you who want to follow a more coherent and basic discussion on this topic, as it relates to Enfields, there's an similar thread titled Frosting (click here) started by Tom Martin, currently on the go in CSP's Lee Enfield forums.

I found it much easier to follow .........

As the owner and moderator of this site, I really work hard to avoid jumping into threads, to perhaps influence it with my own personal opinion, but with this one, I felt compelled to throw in my two cents worth, which I expect also represents the views of the majority of members reading it.

Thanks for listening ......

Regards,
Badger