Cases and Enfields and lube - Oh my!

[ireload2]

I really can't believe that the engineering of that day was so precise they took into consideration the largest possible grain of sand. Dirt, mud and crud is not calibrated to single grains.
My Hakim came from Egypt with dust (not sand) about as fine as talc.
If you look at the chamber of the Snider rifle and the cartridge fired in it they looked visibly different due to no neck in the Snider chamber.
The .38-55 Marlin/Win/Ballard is another tapered chamber with no neck.
It is so goofed up that the chamber mouth can be smaller than a cartridge loaded with a groove diameter bullet. Some cast bullet shooters size the first 1/4" of the loaded round just to get it to chamber leaving the oversize cast bullet to be shot past the interfering case mouth.

A near contemporary of the .303 is the 6.5 Arisaka another rifle that normally has about .010 clearance between the chamber and the case head.

Original British engineering drawings would probably answer a lot of our questions about chambers and ammo.

[sprog]

"Depth of Rifling .005-.008", now thats 19th century quality control standards for you.

The old Krag rifles had bore diameters that varied to some extent, usually enough oversized that Bannerman was able to set Krag barrels back a few threads and rechamber them to .303 for the 1901 Springfield actioned training rifles he sent to the British in 1915.

Such a wide spread of acceptable bore size is probably why some bores couldn't seal properly even with the card wad, and suffered severe erosion after relatively few rounds were fired.

I've seen bore diameters listed from .309 to .318 major dia being found on Enfield No.1 rifles. I doubt the AK varied that much, the pre WW2 Mosin Nagants did though.

Reynolds tells of experiments using bores of various dimeters and bullets of various diameters, all within the accepted tolerance range. He said that best accuracy was with the .312 bullets in the .310 bores. Guess thats another mystery solved as to why some Enfields are extremely accurate while others shoot Minute of man groups at fifty yards at best.

I looked up the acceptable "Figure Of Merit" for the .303 MkVII ammunition, its listed as 8 inches average at 600 yards, thats not that good at all. It at first appears to mean 2.5 MOA, but actually means no more than half the shots would hit within a 2.5 MOA grouping. Ranges beyond 600 were academic, they weren't expected to be able to hit a man sized target at that range. According to "Sniping in France" chances of making a headshot beyond 400 yards were so slim, even with a good scoped rifle, that even trying was considered an un necessary waste of the rifle's accurate bore life.
I've been able to keep my groups sub MOA out to three hundred yards, using my taylored handloads, so lack of precision accuracy had to have been due to the quality of British MkVII ammunition.
The Canadians had little good to say for British ammunition. Apparently all Canadian manufactured .303 followed the original standards set for the round, while the British found their suppliers couldn't produce ammo within those standards. Ross rifles ended up being too close in tolerances to work well with the sub standard ammunition.

Thanks to Ed we did finally figure out the inconsistencies in the quoted pressures for the various .303 military cartridges, that was of great help. Even a blind squirrel finds a nut now and then.

Hey Alfred am I correct in my deduction that in a previous life you were know as GunnerSam?

[Alfred]

The only warning in any Enfield manual I have is when shooting in wet inclement weather with water in the chamber the Enfield will shoot high.

Only a troll would insult the British in an Enfield forum and I apologize to the British and Commonwealth members reading ireload2 postings above, not all Americans share his warped sick view of the world.

Actually the warning you pasted said that in some cases the SMLE receiver could crack at the lefthand wall.

Your constant attempts to make every discussion of technical aspects of these rifles an emotional appeal to national pride, of a nation you are no part of, is ridiculous.
I'm sure you've spent a lot of your time laughing up your sleeve at the UK members who buy into your drivel.
I couldn't care less if some UK citizens hate and envy the US, it doesn't make an SMLE receiver any stronger or weaker than its design and metalurgy made it. But details such as the lefthand receiver wall cracking if the chamber is wet with rain does bring up an interesting point.
Since Long LE owners have said before that they believed the receivers of the pre SMLE rifles were stronger because there was no thumb cut in the receiver wall, and the Lithgow rifles that failed proof when converted to 7.62 failed at the charger bridge mounting holes among other spots, then the retrofitting of the Charger loading bridge and materials removed may have weakned the receivers.
Besides the Chrome Vanadium alloy used for the 2A rifles there seem to be other differences in the receiver design.

[ireload2]

Does anyone have more detail about Lithgow rifles failing 7.62 proof?
Is there any official documentation of it? Did it really happen?
If they did fail proof was it all rifles tested, a significant percentage or just a small percentage failure. What was the failure mode(s)? Did the receiver deform permanently, break or did receiver bridge rivets comes loose?
Were there any political issues involved such as feuding factions for and against conversion?
Is there any documentation such as arsenal reports that is not hearsay?

[ireload2]

Does anyone have any information relating to the failure of Lee Enfields when chambered to 7.62X51?

[Alfred]

Someone scanned a page from Skennerton's book with a sparse account of the Lithgow 7.62 NATO experimental rifles.

Near as I can remember the test loads used were under 70,000 PSI, probably CUP, somewhere in the mid 60 thousands.

A notation was made that the rifles were "Degraded by use of Carbon Steel" in
place of Chrome Nickel Steel.

This might mean the receivers were late war production and made from inferior materials.

Receivers cracked at the mounting holes for the charger bridge rivets among other places, and bolts began to compress after the first few rounds.
After the first few shots showed the rifles were unlikely to hold up, they then continued firing to track the pattern of failure as damage progressed.

The Australians did not normally allow MkVIIIZ ammunition to be used in the Lithgows, this followed British practice, the MkVIIIZ pressures were too high for the No.1 Receivers. MkVIIIZ pressures were close to low end 7.62 Ball pressures, the later are listed at 48,000 CUP or 51,000 PSI in US Military specifications.

Damage from even slightly over recommended level pressures can damage rifles incrementally, as the Litgow experiments suggest. A rifle may show no visible damage, and may survive a number of overloads, till it reaches a breaking point.
Recommended maximum pressures are not meant to be the absolute max a receiver can stand for a few rounds, otherwise proof tests would not be made at higher pressures than service ammo.

An account of a recent failure of a visibly worn No.4 rifle's bolt head when European MkVIIIZ ammunition was fired also said that a No.4 in very good condition handled the same loads with no problems. The difference between the two rifles was in the level of wear of each.
Battle Rifles are not expected to remain in pristine condition after years of combat, so a wide safety margin is necessary.

[ireload2]

Having seen a 1918 Lithgow #1MkIII* receiver with the charger bridge removed it would be very easy to crack one at a rivet hole. This is because there is very little meat around the rivet holes on the left side of the receiver.

The use of carbon steel is some what vague since it does not imply what % of carbon.

I continue to be puzzled about failing bolt heads.
A properly manufactured bolt head is like a small anvil. It is solid and it is under compressive forces. I can understand if a projection breaks off but the solid body of a bolt head would be very difficult to damage without breaking the bolt body.

[Alfred]

I continue to be puzzled about failing bolt heads.
A properly manufactured bolt head is like a small anvil. It is solid and it is under compressive forces. I can understand if a projection breaks off but the solid body of a bolt head would be very difficult to damage without breaking the bolt body.

I gave this some thought and the photo of one broken bolthead and descriptions of others rang a bell finally.

FN manufactured Mausers once had a habit of the left hand locking lug breaking away. It got bad enough that people were buying WW2 surplus K98 bolts to replace the FN bolt.
The problem was traced to a too sharp agle where the ejector slot was milled.
They began giving the cut a radius at the corners like German Bolts had already had, and the problem went away.
The extractor slot is where gas is usually directed by any case failures in an Enfield, the manner in which the slot is cut may direct forces that can split the bolt head.

Having seen a 1918 Lithgow #1MkIII* receiver with the charger bridge removed it would be very easy to crack one at a rivet hole. This is because there is very little meat around the rivet holes on the left side of the receiver.

The use of carbon steel is some what vague since it does not imply what % of carbon.

See the thread on Indian Proof Testing, it tells of a substitute steel used for Indian Rifles from fifties to mid sixties, and numerous failures in proof testing even at .303 pressures. Also many were passed with only a single dry chamber proof load rather than one dry and one oiled.

[jmoore]

Dang, I almost hate to add fuel to this fire, but I've fired about 1000 rounds of South African ball (174 gn. boat tail) which chrono's at 2550 fps out of a couple of Aussie No 1's, not to mention the additional rounds out of No 4's and a few from a Mk V (plus some other stuff). No headspace changes, over-rotating/broken bolt heads, or anything but excellent results!

[Bindi2]

I have been shooting No1s since the late 60s my father long before that and i have not seen any rifle failure yet. No4sand No5s conversions on all three and still no failures. I also reload have had problems with reloads but still no rifle failures. Can not say the same for later made popular makes.