Question about case life with the #4 in 7.62 NATO?

This document gives the acceptable Chamber Pressure of a number of US Military 7.62X51 cartridges, some are listed in both CUP and EVPAT PSI measurements.
http://www.everyspec.com/MIL-SPECS/M...T3).008538.PDF

Many of these are listed as generating 48,000 CUP and 51,000 PSI, only the M118 Long Range Special Ball is listed at 52,000 CUP.

51,000 PSI is only 3,000 PSI above the maximum SAAMI pressures for the .303, so its likely catridges loaded to pressures no higher than 51,000 PSI would be safe enough for the L42 rifles that passed proof were marked on the Bolthead with the 19 Ton markings. If the .303 rifles bear an 18.5 Proof Mark then the one half ton marking should translate to the rifle being safe with cartridges loaded to 48,000 CUP (about that of MkVIIIZ MG ammunition) or 51,000 PSI, which is far below the maximum pressures now allowed by the MOD for 7.62 NATO ammunition.

The L42 went out of service around the time that the much hotter M118 Special Ball came into use. Its highly unlikely that the L42 was ever authorized to use ammunition loaded to chamber pressures this high.

Also since the rest of the US Mil Spec ball ammunition suitable for regular combat use in battle rifles is listed at pressures of 48,000 CUP its likely that M118 Long Range Special Ball is not considered suitable for all NATO rifles, and it does not meet EVPAT standards.

Conclusion would be that the L42 is not suited to higher pressure 7.62X51 loadings and not suited to the highest pressure .308 Winchester ammunition.

Quote:

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2) What has pressure differences between a 303 and a 7.62 got to do with it ? The original question was case life in a No4 7.62

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The No.4 rifle was designed to handle WW2 era .303 ammunition with a decent margin of safety.
Chamber pressures a rifle was designed to handle safely are very important to handloading for the individual rifle.
A .308 load that is safe enough for a modern Long Range Sniper Rifle that is manufactured to SAAMI standards may not be safe for a converted WW2 era sniper rifle when chamber pressures as high as 62,000 PSI were not envisioned for the 7.62X51 NATO cartridge when that conversion was aproved. The rifle was never proofed for cartridges producing 62,000 PSI and if it were built today it would still not be required to be proofed for use with cartridges of that pressure range by MOD standards.
Pressures of 62,000 PSI would be excessive for the L42, its not proofed for this pressure level and never would be.

I want to hear information from the folks that own a #4 that has been converted to 7.62 and their case life experience. I have no interest in all the cut and pastes from manuals and such. The information I need is not in a manual or a specification.

.303 brass is something I can only acquire 3 ways.
1. Buy new expensive commercial brass and fool around with it to insure long life
2. Buy someones old once fired brass that may or may not be a good value.
Some once fired brass may last well some may not.
3. Pay a premium for brass of another cartridge and reform it in hopes of longer case life.
This third option is both expensive and extra work.

7.62 brass is commonly available and is very in expensive. I could shoot my #4 without concern for case life as long as I keep pressures low. Which I will address in the next post.

Y'all buy me a piezo-electric strain/pressure gauge and i'll check my loads. Its out of the Sierra manual and not quite max. I don't post specific data or even share with friends.

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Originally Posted by Alan de Enfield

To me this looks to be going the same way as several of the other threads by Alfred & Ireload2 - starts with a simple (innocent ?) question and then starts to post all sorts of answers to a question that hasn't been posted.

1) I see this as going towards the same argument 7.62 Vs 308 - the original questions was case life in a No4 7.62

2) What has pressure differences between a 303 and a 7.62 got to do with it ? The original question was case life in a No4 7.62

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Alan de Enfield

It will end up with all of us being told to oil their cases to get better case life, below is the link where ireload2 tried to hijack my case forming thread at Gunboards. This thread was locked down by the moderator and then reopened at my request and then locked down again because of ireload2.

Please take notice of the fact I mention people talking about the inherent weakness of the Enfield rifle in the posting below and then ask yourself why Alfred brought the subject to this forum, or better yet what are ireload2 and Alfred trying to “accomplish” here.

Fire Forming Cases W/Zero Headspace - Gunboard's Forums

Then after my thread was locked down for the second time ireload2 signed back on as “Not a Registered User” so he could answer his own question.

Q- Case slippage in oiled chamber? - Gunboard's Forums

I have filled empty fired .303 and 7.62 cases with water and found the water weight in grains capacities are nearly identical.
To reduce the 7.62 loads to .303 pressures you could easily load .303 loads in a 7.62 case if you use good loading practice and work up the loads.

At this point I am only interested in safe economical shooting and a replacement barrel in 7.62 can be had a number of way inexpensively.
Those shooters currently shooting the 7.62 in a #4 already have a good idea how feasible this is.

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Originally Posted by jmoore

Y'all buy me a piezo-electric strain/pressure gauge and i'll check my loads. Its out of the Sierra manual and not quite max. I don't post specific data or even share with friends.

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Hello jmoore,
I have a few questions about your shooting the 7.62 in the #4.

1. I am not familiar with any official designations this version has. Can you tell me about your rifle and it's barrel and chamber?

2. Have you shot any out of the box Nato issue factory loaded or the equivalent factory loaded ammunition in your rifle?

3. If you have fired factory loaded ammo, what was it and how did your rifle perform as far as extraction. When the bolt handle is raised do the rounds pull free of the chamber normally?

4. Does you rifle have a normal or tight chamber? Is your chamber a better fit to 7.62 ammo than the typical as issued barrel of a #4 rifle to typical .303 brass? Do you get a mild or pronounced step at the pressure ring.

5. Can you tell us which powder and bullet you use. We can guess at the rest for modeling with Quick load. Any data you provide will only be used for estimation of pressure. If you don't want to post it you can PM me with the information.

I had considered a conversion long ago when reloadable reasonably priced .303 was hard to find and the Seller& Bellot cases proved to have undersized primer pockets that caused detonations while seating primers no matter how carefully. The primer pocket issue hasn't been mentioned lately so I guess the later production doesn't have that problem. S&B cases were also thinner in the wb and stretched worse than commercial cases and the necks had to be annealed.

7.62 Conversion kits were available at reasonable prices, the thing that stopped me from converting was that I could not guarantee that a relative that the rifle was passed onto years from now might not use unsuitable .308 ammunition, or NATO ammo unsuited to the rifle. The M118 long range Special Ball hadn't been developed yet, but there were and are lots of 7.62 NATO that would over stress the Enfield actions.

Same applies to the 2A Rifles. They may be perfectly safe with ammo loaded no higher than regular Ball ammo , but very un safe with high end loads.

Your best bet would be a custom barrel with tightest chamber and headspace that would accept either cartridge. A Bolt Head for the rimmless case would probably be hard to find though.
Barring that there may be a few unused conversion kits still out there, with bolt head, but would probably cost more than a custom barrel and surplus BH.

Buying a used L8 would be a pig in a poke, no telling what sort of ammo its been fed, and there could be damage you can't see that could cause a failure later on.

All in all sticking with the .303 is the better option.

If need be a No. 4 barrel can be set back one thread and the chamber freshed up to bring headspace within the specs you want using a size O bolthead for thick rim cases , if you ever find any ,and a No.1 bolt head for thinner rim cases if need be.
The bulkhead that the breech buts up to can be ground with a diamond wheel just as they do when blue printing a Mauser action. Cutting it back a few thousandths so the set back barrel seats properly and truing it up at the same time.

The bulk head does not have to be cut back much. Setting the barrel back a full thread is only so the extractor cut lines up.

More work than its worth really. I'm glad I found No. 3 Bolt Heads cheap years ago. I wish I'd bought a dozen then.

I am only considering a single shot conversion. My rifle is not of collector quality. It has an excellent barrel that can be removed and stored for later re- installation. I have an old junk fore end and was considering finding a take off 30 caliber barrel or a retired .30 caliber bench rest barrel for installation.

I learned a long time ago not to worry with buying new factory brass for the typical .303. I had bought once fired brass of numerous different headstamps and none - of it was very long lived.
After some of these adventures in posting I dug out all of my 35+ year old brass to to relive yesteryear. I shot 33 rounds with a total of 10 different headstamps. Three of the rounds were modern .405 Hornady cases reformed to .303. Two were .444 cases that had not been fire formed.
All the head stamps were
WW
RP
Norma
Interarmco
Herters
R-P 30-40 Krag trimmed and sized.
.444 Marlin R-P
WRA 1943
.405 Win by Hornady
HXP with 69 and 83 dates
The HXP brass has significantly varying web heights between the two dates with the 83 web bing about .060 taller.

I used some 40 year old Herters bullets in most of this ammo just for fire forming and the resulting ammo was mostly used for plinking.
A few were shot at targets with the expected unpredictability of such a Heinz 57 mix of brass. Most of the primers came from some that I had inherited from a friend. So they were an added variable. This shooting helped me dispose of some 2nd rate components acquired for nothing while fire forming some ancient brass.
I did have one head separation with an R-P .303 case in spite of very low pressures that failed to fully fire form the Krag brass.

the .405 cases had been formed to have some contact at the shoulder with the bolt closed which is a normal practice for me when forming new brass.
It normally does not produce a marked change in the point of impact.
In the #4 the 3 shots fired hit about 8" higher than the rest of the rounds fired on paper.

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Originally Posted by Alfred

This document gives the acceptable Chamber Pressure of a number of US Military 7.62X51 cartridges, some are listed in both CUP and EVPAT PSI measurements.
http://www.everyspec.com/MIL-SPECS/M...T3).008538.PDF

Many of these are listed as generating 48,000 CUP and 51,000 PSI, only the M118 Long Range Special Ball is listed at 52,000 CUP.

51,000 PSI is only 3,000 PSI above the maximum SAAMI pressures for the .303, so its likely catridges loaded to pressures no higher than 51,000 PSI would be safe enough for the L42 rifles that passed proof were marked on the Bolthead with the 19 Ton markings. If the .303 rifles bear an 18.5 Proof Mark then the one half ton marking should translate to the rifle being safe with cartridges loaded to 48,000 CUP (about that of MkVIIIZ MG ammunition) or 51,000 PSI, which is far below the maximum pressures now allowed by the MOD for 7.62 NATO ammunition.

The L42 went out of service around the time that the much hotter M118 Special Ball came into use. Its highly unlikely that the L42 was ever authorized to use ammunition loaded to chamber pressures this high.

Also since the rest of the US Mil Spec ball ammunition suitable for regular combat use in battle rifles is listed at pressures of 48,000 CUP its likely that M118 Long Range Special Ball is not considered suitable for all NATO rifles, and it does not meet EVPAT standards.

Conclusion would be that the L42 is not suited to higher pressure 7.62X51 loadings and not suited to the highest pressure .308 Winchester ammunition.


The No.4 rifle was designed to handle WW2 era .303 ammunition with a decent margin of safety.
Chamber pressures a rifle was designed to handle safely are very important to handloading for the individual rifle.
A .308 load that is safe enough for a modern Long Range Sniper Rifle that is manufactured to SAAMI standards may not be safe for a converted WW2 era sniper rifle when chamber pressures as high as 62,000 PSI were not envisioned for the 7.62X51 NATO cartridge when that conversion was aproved. The rifle was never proofed for cartridges producing 62,000 PSI and if it were built today it would still not be required to be proofed for use with cartridges of that pressure range by MOD standards.
Pressures of 62,000 PSI would be excessive for the L42, its not proofed for this pressure level and never would be.

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Alfred

You are again wrong in your pressure assumptions on the 7.62 and British Enfield rifles, the American testing and pressure requirements do not apply in the U.K. and the U.K. uses European NATO EPVAT CIP requirements for the 7.62 NATO.

This would be 60,190 PSI and proof pressure checked at 75,275 PSI (transducer method)
and the British 7.62 NATO rifles passed these standards.

The British proof markings that are stamped on the receiver are in the British copper crusher method in long tons and read 20% lower than the American copper crusher method hence the slightly lower readings.

You keep cheating and keep trying to wiggle and fudge the pressure figures around in your favor, sorry the 7.62 British Enfield’s passed their proof pressure testing with flying colors or colours since the testing conforms to European testing standards.

https://www.milsurps.com/images/impo...08proof1-1.jpg

https://www.milsurps.com/images/impo...cipproof-1.jpg

https://www.milsurps.com/images/impo...08proof2-1.jpg
https://www.milsurps.com/images/impo...08proof3-1.jpg

OK kids thread closed due to off topic
Posting and a few other infractions.