Had someone ask me....

[Travis]

The other day I had someone ask me about necking down 7.92x57mm {8mm Mauser brass} to .30cal. or necking up 7x57mm and 6.5x55mm to .30 cal. .

I basically said: "WHY?". You already have the .308 Win. / 7.62x51mm NATO and the .30-06 Springfield. So why try to mimic a round like the .30 Thompson Contender when in the realm of reloading the .30 T/C is nothing more than a gross attempt to try to fix the already unbroken .308 Win. or the .30-06 Springfield with or without Ackley Improvement, it would still not make much sense.

Now one thing would make good sense if you were building a sporterized rifle off of the 7.62x54Rmm round would be to have another barrel chambered in ACTUAL .308" and not in .311" so you could work with more of an actual selection of choices in many different weights and shapes. In other words to follow the milspec parlance you could have soft point Light Ball or Heavy Ball for different hunting applications. This is a VERY accurate caliber and maybe with different reloading applications I'd bet boat tailed ammo would work well.

I do know that American made 7.62x39mm ammo should not be fired in foreign made AK's or SKS's because our ammo is of the .308" size and not .310" or .311".

[stalkingbear]

Your right-I don't think it would be worth the trouble. If you're going to shoot .308 bullets, just load them in an 30-06 and be done with it. If you had a 7.62x54R in .308 bore you wouldn't be able to shoot milsurp ammo any more-and isn't that the whole point of having a milsurp chambering?

[Travis]

Absolutely Bear, Most all of the 7.62x54Rmm is .311", some other foreign manufacturers do make 7.62x53mm for the Finnish captured rifles marked "M-39". But still in all it is still mostly .311" with some cases of the projectile being .308" or .310", whether foreign or domestic made ammo.

Now there are RARE exceptions with 7.62x54Rmm Mosin Nagant's having ACTUAL .308" bores and some folks have shot the larger surplus ammo, some with no detrimental effects, some were not so cool. The Finns were smart when they took the captured rifles and made no more than the barrels and changed other small things cosmetically.

The Finns changed the bore diameter with a newly made barrel because of MANY inconsistencies in the tooling the Russians had when they made their barrels originally. Typically, the bore was made to be .311" but inconsistencies and worn tooling produced barrels up to and including .318"!! Still too large for milsurp ammo or even modern commercially made ammo. .318" is crowding 7.92x57mm which is EARLY 98 Mauser ammo measurements!! The 7.92x57mm ammo is now .323".

The Finns changed the bore to a more even .308" or .310" to accept the firing of even captured machine gun ammo that was left around by the Russians due to being overrun or whatever. And, most Finn marked barrels have a symbol on them like mine does that what appears to be a number that looks like 3600 with another symbol interrupting the 6 and the first 0. While still not causing alarming overpressure in the barrel / chamber.

I have seen several rebarrelled Mosin's or even M-39's to accept the .308" projectile size while meaning the owner of said rifle had to have custom dies made so he could shoot the "new ammo in the new barrel". Mostly so the owner could get a better selection of ammo in projectile weights and configurations so more experimentation could be undertaken.

In the meantime, said owners also had "stock" Mosin's / M-39's for the originality of said weapon as well. If you have that kind of cash, fine, but most folks know that there is not much of a selection in .311" projectiles. Pretty much .308" and .284" rule the American markets, with 6.5mm / .264" coming along in a slow third. .311" also works in 7.7mm Japanese and .303 British rounds as well.