Finn M 39 muzzle measurement

[Griff557]

I’ve had my Finn M39 for quite awhile it shoots PPU 180’s and Ruag 174’s very good (both .311” bullets) just for giggles I measured the muzzle with my 30 caliber ME gauge I was surprised when it read less than .305 The rifle has a 1944 Sako barrel it is not counter bored and the crown looks fine to me. I’ve read there is chance it could be a .308 bore but it would be rare. I have a friend that slugged his 1943 M 39 Sako barrel and used a 30 caliber ME gauge on his M39 and it measures .315” he says his rifle doesn’t shoot that well. I have not slugged/cast my barrel yet - what am Iam missing?

[rcolarco]

If it shoots well, you are not missing anything. Just shoot it and don't worry about it. The only thing I measure is group size.

[Griff557]

I’ll admit Iam not the sharpest knife in the drawer but maybe I’ve solved my own problem? I’ve read Mosins have a nominal bore dia of 7.62” or 30 caliber but it’s the depth of the grooves that determine the bullet diameter you would use. If this is the case it makes sense to me why my 30 caliber muzzle gauge only goes in to about .303” If my theory is right and I were to slug/cast the bore the lands should measure .310-.312” ? or am I all wet ?

[ZvenoMan]

Originally Posted by rcolarco

If it shoots well, you are not missing anything. Just shoot it and don't worry about it. The only thing I measure is group size.

God Bless You sir!

You NEVER hear of ME or TE readings on 99% of non-US Milsurps. Certainly not Mosin Nagants (USSR, Finn, Chinese, etc).
Swede Mausers have the bore disk, and that's as much bore condition as muzzle wear. I can't think of any other milsurps where it is routinely discussed.

Shoot it!

MW and TE are easy measurements to take, the tools to use are not expensive or complicated. But they are only an indication of shooting performance, and in no way 100% indicators of possible performance.

Considering the Garand must be cleaned, using the steel rod, from the muzzle, and no other service rifles of the day did so, MW was a bit more of a concern. Just my guess......

JH

[rcolarco]

Bullets intended for the 7.62x54R are usually 0.312". That is an average groove diameter, not the land diameter, which is smaller. However, you can check loading manuals and find data for 0.308" bullets also. What your rifle shoots best is a question only you can answer.

It is generally best for accuracy to shoot bullets that are sized to groove diameter. Smaller bullets may shoot well, but may not. Larger usually shoot OK, but don't overdo larger.

Bore measurements on Russian rifles are all over the map. Slugging the bore is not a bad idea, but if the rifle is shooting well there may be little point.

Finnish industry usually operates to closer tolerances than Russian, so I would expect Finn rifles to be more consistent than Russian. If you have one rifle, you really don't care about consistency, just shoot whatever shoots well in your rifle.

[Griff557]

Originally Posted by rcolarco

Bullets intended for the 7.62x54R are usually 0.312". That is an average groove diameter, not the land diameter, which is smaller. However, you can check loading manuals and find data for 0.308" bullets also. What your rifle shoots best is a question only you can answer.

It is generally best for accuracy to shoot bullets that are sized to groove diameter. Smaller bullets may shoot well, but may not. Larger usually shoot OK, but don't overdo larger.

Bore measurements on Russian rifles are all over the map. Slugging the bore is not a bad idea, but if the rifle is shooting well there may be little point.

Finnish industry usually operates to closer tolerances than Russian, so I would expect Finn rifles to be more consistent than Russian. If you have one rifle, you really don't care about consistency, just shoot whatever shoots well in your rifle.

Appreciate the info...I only have the one Finn M39 it shoots 7.62x54R PPU and Ruag very good ( I believe .311-.312 bullets) like I said I never gave it much thought until my buddy started measuring/casting his bore and I got curious what mine was. I think a big part of my confusion was I didn’t understand how it was measured. Like you said “just go shoot it”

[hebes405]

Originally Posted by Griff557

I’ve had my Finn M39 for quite awhile it shoots PPU 180’s and Ruag 174’s very good (both .311” bullets) just for giggles I measured the muzzle with my 30 caliber ME gauge I was surprised when it read less than .305 The rifle has a 1944 Sako barrel it is not counter bored and the crown looks fine to me. I’ve read there is chance it could be a .308 bore but it would be rare. I have a friend that slugged his 1943 M 39 Sako barrel and used a 30 caliber ME gauge on his M39 and it measures .315” he says his rifle doesn’t shoot that well. I have not slugged/cast my barrel yet - what am Iam missing?

The finns stamped the 308 bore rifles with a B. Not common and collectable. Most barrels you will see are either not stamped or stamd D. Which means its been set up for the D166 round. Excellent ammo, if you can find it. Lucky for us its easy to replicate.
D166 bullet, 40 grains of N140, COAL 2.992

[WarBaby1942]

Recently bought a Finnish M28-30 made in 1935. Slugging the bore revealed .3082 grove and it has a "D" stamp and inspecting the bore shows a hogged out throat for the D 166 bullet with a rather long bullet jump and some pitting. It was at some time transferred to the Finnish Army because of the boxed "SA" stamp. Has it shot ammo other than .308 diameter? I am guessing maybe hundreds or thousands of rounds. I shoot .308 Sierra 175 grain SMK bullets using 4064 or 4895. I am thrilled with the way it shoots. I found some 185 grain D 46 Laupa bullets in .308 which i understand the rifle was set up to shoot in the beginning but the weather turned rough and haven't shot any of them yet. They will have to go some to beat or be as good as the Sierras.

Oscar/NC

[hebes405]

I've been load developing 123 grain "sks" bullets for my m39. So far it looks promising. It will probably only ever get shot at 200 yards

[USAF Sarge]

Love my Finned Mosin-Nagants, I've got two of them.

1894/1927 Izhevsk/Tikkakoski Mosin-Nagant Model 1891, (1 of 3,000), C coded (3087 bore size) stepped barrel. Between 1925-1927 10,000 got re-barreled, out of those 3,000 received stepped barrels.

1915-1917/1924-1927 Remington/Böhler Stahl Mosin-Nagant Model 1891/24 aka Lotta Rifle.

These rifles have been through a lot, obviously......!