Safe to use .311 bullets in Mosin Nagants?

[Matt Dillon]

Folks, I have a Mosin Nagant 91-30 and a Mosin Nagant M-44. I want to develop a load that will work well with either gun.
Ihave slugged the barrels, but am not sure exactly what diamater I ended up with. The slugs were not completely uniformly round, and at the widest spot came in around .3095-.311.
It appears as though the 91-30 has a longer throat than does the M-44, but I settled on a Cartridge Overall Length of between 2.959 and 2.972 inches.
Is it safe to try and use .311 diameter bullets? I have heard that as small as .308 usually work well in these rifles, but I'd like to develop some hunting loads using the .311 diameter bullets.
My ideal load ( I haven't shot nor chronographed this load yet) would be 48 grains of IMR 4064 behind a .311 150 grain Speer #2217 Spitzer bullet.

I hope to try some of these out this weekend, starting at 44 grains and working up to 48, in .5 grain increments.
Does anyone have any other advice regarding load development for this round?
Thanks in advance!

 

[Third_Rail]

I personally use bullets made for 7.62x39 reloading, and they work great since they're .310 in diameter... I don't use .308 diameter bullets for reloading as I was told that the bullet then has room to slightly "bounce around" in the barrel, a bad thing indeed.

 

[Clark]

In 91/30s, M44s, and M39s, I use Sierra .311 dia. 180 gr. SPT Pro-Hunter Sierra part number 2310 bullets, at 2750 fsp from the long barrels.

The big bullet in a small bore making no pressure increase is counter intuitive.
Likewise the pinched bullet making a huge pressure spike is counter intuitive.
The way I reconcile it is to think in the time domain.
If the peak pressure of powder burn is not concurrent with the increase pressure to swage, the peak pressure does not change.
And if the pinched bullet delays the start of bullet acceleration, the increased pressure makes the powder burn faster which increases pressure which makes the powder burn faster ....

This phenomena of large bullets working in a small bore without
pressure spikes is documented in P.O. Ackley 1966 "Handbook for Shooters
and Reloaders Vol 2" chapter 7
"additional pressure tests":
"..30 cal barrel pressure barrel was fitted to the test gun, but the
neck and throat was enlarged to accept the 8mm bullet, with the bore
remaining the standard 30 caliber. A Remington factory 30-06 cartridge
with the 150 gr bullet had been tested and previously gave 57,300 psi,
for a velocity of 3030 fps. The the bullets were pulled from two more
Remington 150 grain cartridges and were replaced with 8mm 150 grain
bullets. To everyone's surprise, although the velocity was rather
erratic, these loads averaged 2901
fps, with a pressure of 40,700 psi."

I have verified this by shooting .452 bullets in a .410, and .323 [8mm] bullets in a .303 [with turned case neck so will fit in chamber]. There were no increases in pressure signs that I could see. It seems strange.

 

[Cosmoline]

The whole .308 for Mosins thing got started because certain older Finnish Mosins (without the "D" bore) were chambered for .308" bullets. So the fear was that if you drop a .311" cartridge in one of these it might build up too much pressure.

Frankly it's tough to even FIND a Finn these days that wasn't either built or switched to "D" bore. And of course .311 should work fine for your 91/30 or carbine.