Mosin reloading .308 or .311 bullets ? - range test

91_30_150gr.jpg91_30_170gr.jpgM39_150gr.jpgM39_170gr.jpgTwo Mosins.jpg

Over the years I have shot all different kinds of Mosin Nagant rifles with my reloads at my local range. I have used both .308 and .311 diameter bullets at times. The general consensus is that the Russian Mosin's have a .311 bore and the Finnish rifles have a bore in the .308 -.309 range and that the bullet diameter should match the bore size. Today I took two of my Mosin's to my local range and fired some 10 shot groups with both rifles at 75 yards. Why not 100 yards? I have some bulls that are only 8 inches in diameter and my aging eyes really need a 12 inch bull at 100 yards. I can scan and print out on my computer printer an 8 inch bull but not a 12 inch bull.

The two guns used were a Russian Izhevsk 1944 91/30 and a Finnish VKT 1944 M39. Both guns have mirror bores and have proven over the years to be very accurate. I used two loads that I know are accurate with these guns. One load (49 grains AA 4064) used a Remington PSPCL 150 grain .308 diameter bullet and the other load (47 grains AA 4064) used a 170 grain .311 diameter Remington round nose bullet. Winchester primers and Lapua brass was used with both loads. It was overcast with little to no wind. All groups were fired from a steady bench with front and rear sandbags.

What did I find out ...

1. Both guns are pretty accurate.
2. The .311 larger diameter bullet shoots slightly better in BOTH guns than the .308 bullet but not by much.
3. The M39 outshoots the 91/30 but not by much. Better sights on the M39 helps give a better sight picture which evidentally outweighs the slightly longer sight radius advantage (about 1.75 inches longer) on the 91/30. The M39 also has a heavier barrel than the 91/30.
4. The M39 most definitely can shoot better than I can hold and the rifle will probably hold 1 MOA if a scope were used. It put nine out of ten shots under an inch @ 75 yards with the .311 bullet.
5. For all intents and purposes I could (at least in these two rifles) use either bullet.
6. On the 91/30 the point of impact drops maybe an inch at 75 yards when switching from the 150 grain .308 bullet to the .311 bullet. On the M-39 the point of impact does not drop when switching from one bullet to the other but does move about an inch to the left when switching from the .308 bullet to the .311. Probably because of the barrel vibrating differently with the 170 gr .311 diameter bullet.
7. Sometimes having the bore and the bullet size a "perfect match" may not necessarily give the best accuracy.


Bob

Originally Posted by Bob01605

Yes - BUT the point of the test is that sometimes slugging a barrel may not give you the best bullet to shoot? I would be willing to bet that my VKT M39 slugs in the .308 - .309 range as most Finnish Mosin's do. Yet ... It shoots a .311 diameter bullet best. If I had slugged the bore and it was in the .308 - .309 range and I relied totally on that information to select a bullet to shoot, I probably never would have even tried a .311 bullet ...

Bob

OK if you say so.

If I may suggest try slugging the barrel before you assume the results would provide you with the wrong projectile to use.


as a side note....Out of my 198 Mosins Nagant collection, both Finn and Russian it has never been wrong. Buy hey, that's just me.

Information from 7.62x54R.net:
2) Groove diameters vary and Russian/Soviet rifles tend to run larger than the nominal size of .311" to as much as .314". Slugging the bore is the only way to be sure of the exact measurement. .

M39
Groove Diameter .310"