"Metalurgy" Notes

[muffett.2008]

1921, I have the 1914 one also, they vary a bit in spec's required.

[Bruce_in_Oz]

Wait! There's more.

From the 1938 Specs. for the SMLE:

Regarding barrel proof, refer to page 12:

(g) Proof. - The barrel will be submitted with the action attached for proof. The distance from end of bolt to face of barrel will be tested with a cartridge head gauge .067-inch. The proof will then be carried out with a proof cartridge, the charge being about 33 grains of No.3 cordite, having a service bullet of 215 grains, giving a mean pressure not below 24 tons per square inch, after which the action will be examined; and the barrel, body, and bolt head will be marked with the proof mark.

Note:

Composition of the B.S.S.5005/401 steel used in the body (receiver):

Iron (unsurprisingly)
Nickel 2.75 to 3.50 %
Manganese 0.35 to 0.75%
Chrome 0.30%
Carbon 0.25 to 0.35%

So, the SMLE was FACTORY proofed to at least 24 TONS per square inch.

Did Ishapore have a different recipe at the time and did they change it for the 2A1?

[lee_enfield223]

Just an observation I have seen two No4 303 actions in the last 7 or 8 years that have been proof tested for the 7.62 at Lithgow, that were fired with the NSWRA winnchester 308 match load(correct me if I am wrong reg the load)about 46grs of 2208 behind a 155gr sierra,and both developed excessive headspace and the locking lug recess bulged into the bolt raceway, so I guess if a No4 can't take it then I would be worried using that ammo in an indian 2A1 !!!! anyway it's just a thought, but I have also seen those number 4 7.62's fire thousands of proper ex mil 7.62 ammo with no hassles

[Peter Laidler]

On the other hand, while you have seen two No4's that can't take it, as a bit part Armourer of the era I've seen a thousand L42's successfully firing 7.62mm. There will probably be a similar amount of No1 conversion's in Idian service that use 7.62mm NATO spec still using it.

I think that you're scaremongering a bit.......... Just my thoughts for what they're worth

I only ever saw two catastrophic failures with No4's in my service. In fact, I didn't actrually SEE them, but saw the results of the Board of Enquiry findings. None of which were rifle failures as such but user error. Loads of broked parts etc etc but major failures, just two

[bigduke6]

I have tested lots of loads in military chambers and found that you can load more powder into a rifle with a long throat

Is there really any need to "stoke up" the powder, I,m the other way when it comes to my Milsurps, but I think Bruce in Oz explains the throat very well in post #17,

[303Guy]

For what it's worth, 47gr of Varget (2208) under a 155gr Sierra bullet produces 49,400 CUP in a 308 test barrel according to Hodgdon. ADI lists the same load but don't show the pressure or the bullet type (they normally list Hodgdon data). The extrapolated pressure can be expected to be around 46,700 CUP with 46gr in the same test barrel. An overload would seem to be unlikely as 46gr fills the case without compression.