NRA Safety Notice re No 4 7.62mm Conversions

[PrinzEugen]

Getting back to the issue of the NRA warning - isn't then a case of 'as you were chaps' unless I'm reading it wrong? An enforcer, l39 etc is effectively cleared as completely safe?
As people have mentioned - not too much of a shock for a proof house to suggest people get their guns proofed. Next thing, Kwik Fit will be suggesting people get their brakes checked.

[ireload2]

>>>Is there any scientific proof that the steel in these areas is “compressed” or displaced?<<<

The bolt is compressed momentarily and the receiver is stretched momentarily. The members of a rear locking action under load are longer and deform momentarily more than the shorter members of a front locking action.
This will be the case until the laws of physics are repeals.

Tis a fact of life. Engineering books are full of the information.
Steel is indeed elastic. Ask Mark Knopfler. He is extremely familiar with the elastic properties of steel and has made millions with his abilities. He even lives in the UK.

[Edward Horton]

I'd hazard a guess that the oiling was introduced to enable the generation pressures that the propellants of the time may not have permitted in many case sizes, and that modern propellants have made that step unnecessary.

Going back a bit in this thread, bolt head overturn is surely caused mostly by simple mechanical wear to the contact surfaces on the threads of the bolt head and bolt sleeve, together with wear to the front face of the bolt sleeve where it contacts the rear face of the bolt head. As the threads wear, they take less of the thrust, allowing the bolt sleeve face and bolt head rear face to wear against each other with more and more force, causing accelerated wear of those surfaces. I've seen a few boltheads with quite striking grooves worn in them by the front of the bolt sleeve. Now I could be wrong about this, but it seems to me it would make more sense mechanically to have the thrust taken by the far larger surface area of the threads than by the forward face of the bolt sleeve,, as has been suggested here and in another thread.

Likewise the “setback” of bolt lugs and recoil lugs in the body. Is there any scientific proof that the steel in these areas is “compressed” or displaced? Surely the loss of dimension on those surfaces is caused almost entirely by simple mechanical wear as the surfaces rub against each other every time the bolt is opened and closed?

But perhaps I'm just misunderstanding...

Surpmil

1. Even today British military proof testing of small arms is done with oiled proof test cartridges, the oiled proof round exerts twice the force that a combat military rifle will ever see in actual combat conditions. (Firing in the rain)

2. If you have bolt head over turn past the 20 degree mark the threads get “hammered” when the rifle is fired. Under normal conditions and minimal bolt head overturn or rotation the mating surfaces of the bolt head and bolt body take the force of firing. You do NOT want the threads to take the force of firing a cartridge, you will screw up the threads and jam the bolt head.

3. In the Text Book of Small Arms after the proof round was fired the Enfield was checked with a .067 headspace gauge and if the bolt closed on this gauge the Enfield failed proof testing due to excessive bolt setback. It does not state this in the book but I assume the headspace was set as close to .064 as possible before testing. An oiled cartridge exerts twice the force on the bolt and lugs than a dry cartridge does, therefore it causes twice the wear and the effects of excess bolt thrust over time are accumulative. (If you keep letting someone hit you over the head with a baseball bat your going to get a headache and the guy with the bat is going to leave an impression on your mind)

[Surpmil]

>>>Is there any scientific proof that the steel in these areas is “compressed” or displaced?<<<

The bolt is compressed momentarily and the receiver is stretched momentarily. The members of a rear locking action under load are longer and deform momentarily more than the shorter members of a front locking action.
This will be the case until the laws of physics are repeals.

Tis a fact of life. Engineering books are full of the information.
Steel is indeed elastic. Ask Mark Knopfler. He is extremely familiar with the elastic properties of steel and has made millions with his abilities. He even lives in the UK.

Yes, the stretching and flexing part I knew about. I had the (mistaken?) impression it was being asserted that this was a permanent change.

Mr. White (was it?) thinks the body of his No1 MkV has "stretched" according to his reply to Alan d'Enfield's letter. I wonder how he 'knows' it has done so, rather than just worn at the bearing surfaces?

[Mk VII]

You will never get the NRA to admit they are wrong. They would rather maintain their position than lose face.

[coppertales]

This whole deal falls under the "FOLLOW THE MONEY" sniff test. It seems the British are looking at another way to remove servicable rifles from use in that country by making the inspection process impossible to follow. On the other hand, just buy an Indian 2A or 2A1 and be done with it. They were built to shoot 762x51 ammo.
This whole exercise is a bit after the fact. Enfield 303 rifles have been around for over 100 years. If the British followed today's claims, they would have lost two world wars......chris3

[Alan de Enfield]

This whole deal falls under the "FOLLOW THE MONEY" sniff test. It seems the British are looking at another way to remove servicable rifles from use in that country by making the inspection process impossible to follow. On the other hand, just buy an Indian 2A or 2A1 and be done with it. They were built to shoot 762x51 ammo.
This whole exercise is a bit after the fact. Enfield 303 rifles have been around for over 100 years. If the British followed today's claims, they would have lost two world wars......chris3

Enforcers, Envoys, L39, L42 etc were all 'built' to shoot 7.62 x 51.

The argument from the NRA is that they are (were) not strong enough to use the 'hot', heavy bullet, ammo that the NRA is issuing for their competitions.

The NRA accepts ( I think) that the No4 action is stronger than the No1 action, so I dread to think what they would make of a 7.62 No1 based rifle.

[Patrick Chadwick]

Dear Strangely Brown and others,

if any of you are NRA members, could you please get the message across to them that the following information "throat diameter is less than the CIP specification of 0.311” but not smaller than 0.3085”
is

just

W R O N G

and, in fact,

D A N G E R O U S

as it implies that some rifles may have thoats as tight as 0.3085, and that would be OK .

(Sorry lads, but sometimes one does have to shout!)

All CIP linear dimensions are in mm. Perhaps one of you could donate a cheap pocket calculator to the NRA, as they are apparently unable to convert millimeters into inches.

Please see my comprensive posting on the "bad publicity for enfields" thread.

A 308 WIN chambering with a throat (CIP term : "Commencement of Rifling") diameter less than 0.3098" is BELOW the minimum value. That will, of course, raise pressure with any type of ammo. It does not matter whether the rifle is an Enfield, Swing, Tanner, Grünig and Elmiger or whatever. So why pick on the No. 4?

Patrick

[Bindi2]

The Aussies converted some No1,No6 actions to 7.62. They all failed which was the end to that trial only No4s survived and were convereted en masse

[Surpmil]

AFAIK, the only thing that seperates a No4 Mk2 from an Enforcer, Envoy, L39 etc. is the hammer-forged RSAF(E) barrel and the extractor & mag. In fact, a bit of 'meat' is milled out of the mag wells for those conversions (at least the first two) so those bodies must in fact be very slightly more 'stretchy' than their .303 equivalents!

The No4 Mk2 bodies and bolts that were used to build the Enforcers & Envoys etc. are otherwise identical to the .303 pattern they were originally built as, as of course we all know.

Since when has bullet weight been an issue in proofing? .303 MkVII has been loaded with everything from what, 150 grains to 215, and with never a safety issue AFAIK. So now 15 grains more bullet in 7.62mm is suddenly grounds for re-proofing and all kinds of hoopla?

Surely bullet diameter is the significant issue in relation to pressure?

As for the 7.62mm SMLE, I wonder if they've sent an urgent "safety warning" to the Indians yet?