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Lead melter
05-08-2008, 08:00 AM
So I slugged the barrel of my M-49 Moisin-Nagant this morning and after repeated measurements I keep coming up with the same things

The diameter, at the smallest point of the lands is .304" The smallest diameter of the grooves is right at .3145".

Strange thing is, shooting the Lee C312-185-1R as cast [.312" across the mold, .313" at the part line] with just the gas check bump crimped to about .316", or with the boolit sized to .313" still gives me really good accuracy in my 50 yard plinker load with 10-12 grains Unique. I also get very good accuracy with the stock .311" condom bullet in factory ammo.

Have I done something wrong while measuring the barrel slug? Is the boolit bumping up enough to fill the grooves when fired? Reckon the boolit swages into the grooves enough to give rotational stability?

Can't figure this one out. Anyone have a barrel like this? Any ideas are welcome.

Ricochet
05-08-2008, 09:28 AM
Those are normal dimensions for a Mosin-Nagant of the '30s-'40s era. If you're getting good accuracy with what you're shooting, you're doing fine. Don't worry.

runfiverun
05-08-2008, 10:15 AM
i've heard of them and the enfields running up to 317.

leftiye
05-08-2008, 12:44 PM
Twould be easy to size a .308 down to .305 and paper patch.

JeffinNZ
05-08-2008, 06:13 PM
I would have said that was a tight Mosin barrel.

nicholst55
05-08-2008, 06:30 PM
I've got one Mosin that mikes about the same; another made in 1942 has a .316" groove diameter. It's currently being rebarreled with a .308" groove diameter aftermarket barrel.

Buckshot
05-09-2008, 03:16 AM
.................The M-N's have comparatively wide lands. Theyr'e about 2/3's the width of the grooves vs a Mauser or Springfield @ 25% land width. It's possible that there is enough lead displacement taking place that those loads are working like they do.

.................Buckshot

Lead melter
05-09-2008, 05:22 PM
I noticed that too Buckshot, it just didn't register with me. Interesting observation...sounds feasible.