Yesterday's Weapons Forums

I've heard that some Finn M39's have a .308 bore. If that is true, how wise is it to shoot Soviet surplus ammo that was made for .310-.312 bores?

The important thing to look for on any model Finnish barreled rifle is a large letter "D" on the barrel. This means that the chamber has been throated to accept Finnish and Russian ammo and will not generate excess pressures. If you are in doubt get someone to make a chamber cast that includes the first 1-1/2 inch past the chamber and see if the throat diameter is at least 0.311-0.312 inch. After the bullet starts moving it is swaged to the bore and groove diameter of the barrel and does not produce excess pressure. Almost all of the Finnish barrels I measured were tighter than the Russian barrels if they were in very good, little used condition.
The stated groove diameter for the M39 in particular was 0.310 in., but Finnish Nagants can have a differing stated groove depending on the model and differing actual diameter due to tolerances.
Some Finnish barrels are reported to have a groove diameter of as little as 0.3082- 0.3086 in.

The smallest groove diameter I have measured is 0.309 in some Tikka barrels. A lot of pristine finnish barrels will measure about 0.310- 0.311 in. groove diameter.

I've got an M39 that I use for hunting (it's one I rescued from a bubba job). I started by rolling some 7.62 with 0.308 Sierra bullets... they tumbled... went up to the 0.311 (S&B) - thing suddenly became a tack driver...

This is an update on the M39. According to other sources many M39s and WWII Finnish Nagants did not have the D marking since it had become standard for all to use the D ball round. I have had over 15 Finnish Nagants all accepted the Russian ammo, but "Caveat Emptor"

later m39's didn't always have the "D" stamp, like oldernavy said. It was standard by then, and they thought the stamp wasn't needed.

the rifles with .308 bores are the early tikka m91's with the "B" chamber stamp on them, iirc. many of them had the "D" mod done later and stamped on the shank also, but that didn't change the bore size.

I've heard that 28/30's also had .308 bores, but haven't researched that lately, memory doesn't last that long anymore!

y'all have a good day, Keith

OK, I went to mosinnagant.net and Ted's site and looked up the info, here it is:

finnish m91's, by barrel shank marks. may have a "D" added later as it was modified for throat:
A, .3106
B, .3095
C, .3087

M27, .3095
M28, .3095
M28/30, .3082
M39, .310

so, an early tikka m91 with the "C" marked barrel shank and an m28/30 would be the ones that are a handloaders dream with .308 bullets, I guess.

Keith

Thanks for all the replies--looks like I'm safe with the surplus ammo.

Always appreciate the great information that is available from the members.

This "D" stamp was the throat size not the bore diameter.