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

[Bob01605]

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

 

[USMA-82]

Nice work - very thorough report.

I find it particularly interesting that the POI would move LEFT with the change in load. Up or down, sure - but left? Nice shooting, though. Simo Hayha woud be proud.

*

 

[Boris]

outstanding! I've seen people discussing this topic and consensus was that tighter bullet is better than looser, while you got to be careful with loads and diameter. There are some drawbacks to each, though. Very nice!

 

[noddaduma]

Excellent report! You may see a greater change in performance at longer ranges

 

[brass hound]

great report i have both rifles .and just starting to reload for them my m39 sluged at .310 i have some hornady 174grn .310 to try will post results

 

[50 BMG]

This is why I slug every Mosin rifle barrel when I buy one. If you don't its trial and error.

 

[Bob01605]

This is why I slug every Mosin rifle barrel wen I buy one. If you don't its trial and error.

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

 

[55_grain]

Hi Bob,

Nice groups! Q: how do your groups compare vs milsurp ball ammo?

I've had similar reloading results with a Type 99 Arisaka (7.7x58 mm). Shoots surprisingly well with both .311 and .308 projectiles, not enough data yet to say that one is better than the other.

55_grain

 

[Bob01605]

Hi 55_grain,

In all honesty, I have never used any milsurp ball ammo in any of the Mosin's that I own. I usually just buy either the raw unfired brass or get some S&B loaded ammo and save the cases after shooting the ammo.

I also have a Finnish M91/30 that I had Jim Roberts make into a "sniper" model for me with a reproduction PU scope. Last year I tested this gun and it preferred the .308 Remington 150 grain bullet over the 170 grain .311 bullet. It also preferred 4064 powder over 4895 powder. I then did a 100 meter test with this rifle and the best load that I found for it. There was a post on this forum at the link below about this test.

http://www.northeastshooters.com/vb...range-report?p=2134985&highlight=#post2134985

Bob

 

[50 BMG]

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"

 

[TZCHRIS]

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. See the illustration below for an explanation of the relationship between bore diameter and groove diameter.

Woa! 198, I bet you wouldn't even notice if one M44 was 'missing' Boy I'd love to get one of them!

 

[50 BMG]

Woa! 198, I bet you wouldn't even notice if one M44 was 'missing' Boy I'd love to get one of them!

I count them every night...

 

[mac1911]

All this can be frustrating. I finally got around to slugging my bore on my hex 91/30.
Lands slugger out at. 301 grooves. 313 I am ordering a Lyman 324xxx mold for cast bullets and will size to 314 with gas checks. I tried some 310 cast I had on hand @ 50 yards it was sad accuracy wise.
what gets a bit frustrating is there is not a heck of lot of data between my 3 books and its mostly. 308 bullet data for fmj.
I pulled what surplus ammo I had open and the bullet measures. 310. Is there any known surplus that is loaded any larger.

I plan on ordering a few bullet choices for my mosin. To start I would like to grab a box of hornady 3131 ht fmj with a .312 dia. I have not researched deeper for more bullet choices. I rather play with cast bullets as its so much cheaper. 99% of my mosin shooting will be 100 yards so super accurate full power loads are not really needed.

 

[50 BMG]

I pulled what surplus ammo I had open and the bullet measures. 310. Is there any known surplus that is loaded any larger.

I plan on ordering a few bullet choices for my mosin. To start I would like to grab a box of hornady 3131 ht fmj with a .312 dia. I have not researched deeper for more bullet choices. I rather play with cast bullets as its so much cheaper. 99% of my mosin shooting will be 100 yards so super accurate full power loads are not really needed.

I have two boxes of Finn ammo from 1943. I will drag it out and measure it. I never thought
till now to see what size projectile they may have used.

It can be frustrating I agree but once you find the correct projectile the rifles shoot as they should. I bet there are countless folks out there just staring out who think that their bore is shot out and sell their rifles when it may only be they are not using the correct sized projectiles.

 

[mac1911]

I thought I had my bore clean until last night. I cleaned until patches game out clean. Then I did the electric bore cleaning!!!! I re slugger and got the same measurements.
I was a bit shocked it didn't increase a little.....I cant believe how much gunk came out.
I'm doing one more electric bore cleaning as I'm still getting some blue patches.
Before all of this off the bench this rifle shot about 7 moa. With the. 310 dia bullet (Hungarian)ammo. I'm going to post my bullet reloads.

My plan is to order some hornady 3131fmj ht bullets. They measure. 312 I have a tin of Russian silver tip that I hope will ne 311 dia bullet. I will pull those and reload into non corrosive platform. I know every gun likes certain ammo BUT this can be crazy not knowing bullet sizes. I pulled some winchester white box and it was 308dia bullet

 

[mac1911]

Not sure what happened but cant edit my post......anyway
I'm sure this rifle will do well with correct ammo.
http://7.62x54r.net/MosinID/MosinAmmo.htm this has some info on what surrplus ammo was loaded with bullet size. I don't plan on shooting much of the surplus through this rifle if I find a nice pet load. Now I just need some boxer primed brass. I traded off what I had before I thought about this project!