Bizarre Safety Warning from the NRA

[Alfred]

so is my '66 2a1 gonna blow up?

I wouldn't feed it any M118 Long Range Special Ball, or any of the heavier loads using bullets that are long enough to take away effective case capacity, such as 200 and 220 grain bullets.

M118 LRSB already exceeds UK maximum pressure for 7.62 Ball at its normal working pressure of 52,000 CUP and has a maximum deviation of 57,000 CUP which is pushing proof test loads for modern UK 7.62 rifles.

Using a loading that generates more than the design pressure limits may not blow up a rifle in good condition, but will cause excessive wear.

PS

On a similar note, I once tried an interesting experiment with a Mod 38 Carcano carbine. This was to fire a standard steel-cored 7.62x39 round out of the unmodified 6.5x52 chamber and barrel. The barreled action was lashed to an old car tyre, the round clipped under the extractor and the fun initiated via a long string.

BORING!! The bullet hit the backstop about 25 yards away. The action opened normally. The steel case had considerably less taper than previously and there was no sign if excess pressure on the locking surfaces. The steel-cored, steel-jacketed bullet had jumped the gap to the chamber neck, been squeezed down a bit and exited, probably not quite intact, in the usual manner. That action was subsequently rebarreled to 7.62x39 as a single-shot kids training rifle and is still in use twenty years later.

I wouldn't be puttng any .30 AP rounds down a 6.5 bore. Most Soviet era AP isn't really AP its just mild steel core with a layer of lead between core and jacket.
I've found some 7.62X54 that had cores easily scratched with a file and others in the same mixed headstamp lot that were harder than a file.
I've found these steel core bullets work fine in my two groove Savage bore.

I can see a Soviet steel core bullet squeezing the lead layer out the open base leaving the core in the jacket. I'd like to see that bullet.

With the difference in case length I'd expect a large portion of the propellant gases exited before the bullet reached OR.