Author Topic: Rebarrelling a Mosin-Nagant? (Read 1956 times)

saands · « **on:** March 04, 2003, 08:36:24 AM »

Does anyone know what the thread diameter is on the Mosin-Nagant rifles ... specifically the Russian M44 and the Finn M-39?

Thanks,
Saands

hubel458 · « **Reply #1 on:** March 04, 2003, 04:36:24 PM »

Saands--Threads are 16-V -- .980 outside thread diameter--threaded section is .937 long.Hope this helps. Ed.

saands · « **Reply #2 on:** March 05, 2003, 01:49:42 PM »

Thanks Ed!

That is EXCELLENT news as the Remington 700 take-off barrels could be used ... just like the Turk Mauser ... I need to look into the feeding/extracting of a rimless case in the Mosin-Nagant ... but a 308 is looking like a good idea! Any experiences out there with this kind of project?

Thanks again,
Saands

John Traveler · « **Reply #3 on:** March 05, 2003, 02:10:41 PM »

Gee, Saands,

I like to do odd smithing jobs too, but rebarreling an M1891-designed Mosin-Nagant?

I guess the simplest question is, WHY would you want to do THAT?

I would be a mite concerned about the safety of that project. The 7.62 NATO/.308 Winchester developes lots more pressure than the old Soviet 7.62 rimmed cartridge. The action is not nearly as good at handling escaping gas as an M98 or even the Jaanese Arisaka. I believe the late, great P.O. Ackley rated it as one of the weakest of the bolt actions.

For another thing, the rimless .308 wouldn't be reliably extracted by the 7.62 Rimmed Russian extractor, even when modified. The boltface cutout is too large. Feeding would probably be okay, because length and shoulder dimensions of the two cartridges are close.

This reminds me of the time a young Marine told me that he fired 7.62mm NATO ammunition in the Soviet 7.62mm rimmed Russian weapons (M1891, M44, SVT, PKM machine gun, etc). After checking the cartridge and chamber dimensions, I guess you CAN FIRE it, but it's probably not a good idea! That 7.62 NATO base is smaller than the Russian by a couple dozen thousandths of an inch!

I guess what I am saying is, POSSIBLE and PRACTICAL are two different things!

Best of luck in your re-barreling project!

Hud · « **Reply #4 on:** March 05, 2003, 04:01:10 PM »

I used to have a Mosin Nagant that had been rebarreled to 8MM mauser by the Polish goverment. It had a whole new bolt as they had to change it to be used on the rimless case. Now it'd be too much work to go through for what you'd end up with.

saands · « **Reply #5 on:** March 07, 2003, 11:41:32 AM »

John,

The "why" stems primarily from the widespread availability of both the M-N's and non-corrosive 7.62x51 ammo ... the Mausers which were once ubiquitous are now becoming harder to come across ... especially in a condition that makes you feel like it is worth going forward. You can still get essentially unissued M-44's ... and for only $70.

As for pressure, when I looked up the numbers, it seems that the 7.62x51 has a max of 60,190 psi (Piezo) and the 7.62x54R has 56,564 psi measured the same way. Pressures being high are really only of concern to the chamber walls ... the bolt really cares about the force that is imparted on it ... more specifically on the lugs. The force is a function of both pressure and area (F= P*A) and when you take into account the area of the bases of the two cartridges, you notice that the 54R produces just about the same force on the bolt as the 51 when both are loaded to MAX pressures ... actually, the 54 ends up being half a tad higher. This also makes sense, anecdotally, as the 7.62x54R throws a 150 grain bullet out there at 2700 fps which is essentially the same as the 7.62x51 ... well within 50 fps anyway.

If it sounds like my reasoning is flawed ... do me a huge favor and please point it out !!!!

As for the bolt question, it looks like I'll need to look at that some more, because the bases of the 8x57 and the 7.62x51 are essentially identical ... if the 8x57 needed a new bolt, that doesn't sound good!

Thanks to all for for the input ...

Saands

Hud · « **Reply #6 on:** March 07, 2003, 01:41:36 PM »

Saands,

I "assumed" the bolt had to be changed, as it's number did not match the action's serial number. But maybe it had been changed for other reasons.

Hud

gunnut69 · « **Reply #7 on:** March 07, 2003, 08:00:46 PM »

There is a vast disfference in the size of the bolt face of the 7.62 Russian and the Nato round but I have seen bolts 'bushed' to smaller cases. In one instatnce a Krag was bushed to accept a 218 Bee case head. The rifle was used a single shot. That brings up the largest problem...what about the magazine.. The MN is designed to feed heavily rimmed cases and will I'm sure have some issues with the rimless cases of 308.. Good luck from the gunnut69

saands · « **Reply #8 on:** March 08, 2003, 09:41:47 AM »

Hud,

Thanks for clarifying that ... did it feed the 8x57 out of the magazine alright?

Thanks,
Saands

Rick Teal · « **Reply #9 on:** March 08, 2003, 10:24:27 AM »

If the current barrel is OK and you just want the gun chambered in a new cartridge, you may want to try the .303 British or .303 Epps. I have a Tokarev that was rechambered to .303 British, so the change is do-able.

saands · « **Reply #10 on:** March 08, 2003, 12:56:45 PM »

303 Epps??? Now that's not one that I had not heard of ... but a quick search shows me that this is the 303 without the mini-case life that had me totally discounting it as a possibility! That's an interesting alternative in the improved shoulders look to be able to give 2800 fps out of a 150gr bullet with moderate (53,000psi) pressures and the same basic geometry as the 7.62x54R. Interesting ...

Thanks,
Saands

gunnut69 · « **Reply #11 on:** March 08, 2003, 07:59:23 PM »

Be cautious as the 303 Brit and it's wildcats use a different bullet diameter than does the 7.62x54..

Rick Teal · « **Reply #12 on:** March 09, 2003, 06:46:04 PM »

gunnut69:

I have it from several sources that the 7.62X54 (like the 7.62X39) actually takes a .311 bullet. There is no apparent rebarrelling or reboring on my Globco (Tokarev), so I tend to believe these reports.

Rick

gunnut69 · « **Reply #13 on:** March 10, 2003, 06:50:39 AM »

I am sorry, you are of course correct.. Must have been the time combined with all those years... In any case the 303 and 7.62 Russian do use the same bullet diameter..

saands · « **Reply #14 on:** March 10, 2003, 02:34:12 PM »

I confirmed that with my micrometer when I first got the 7.62x54 and pulled a bullet out of the mil-surp ammo that I had ... measured it and weighed it (149 grains on that batch) then oreded some 150 gr .303 Brit JSP hunting bullets and made myself a box of hunting ammo in about 15 minutes, being careful to seat to the same depth as the original ... it is corrosive hunting ammo, but one of my rules is ALWAYS to have hunting rounds available for every caliber ... you just never know what you'll need nor when :eek:

Thanks,

Saands

Mikey · « **Reply #15 on:** March 11, 2003, 04:56:06 AM »

saands: why bother with the re-barrel? I read your posts and your reviews of the ammunition issues and feel you may have shorted yourself here a bit, friend. I have known a couple of guys who have picked up the M-Ns and just love them in the original caliber. The 7.62x54R doesn't give anyting up to the 308, period. Sellier and Bellot make some fine hunbting ammunition for that caliber with a 200 grain bullet, the original loading. My younger brother picked one up and is very happy with it.

The 7.62x54R originally took a .308 diameter bullet. Due to bore size variations you may have one with a .310 or even a .311 bore but due to chamber restrictions it is not wise to reload .311 bullets. This comes right from the Lyman 45th edition.

If your current M-N has an oversized bore and doesn't group modern, and current, production hunting ammo, at the cost of these things you may wish to locate another one wiht a better bore. when my brother found his, it was sitting in a barrel with 20 other M-Ns and he just picked the one with the best bore. After we removed the bayonet assembly it grouped like a new rifle.

The concept of rebarrelling a M-N or an 8mm Mauser to 308 has surfaced before and the general response has been not to bother. Neither cartridge gives up anything to the 308 and many even surpass the 308 using original european loadings. Every American ammo manufacturer has downloaded the european cartridges so far that many folks seem to think they are worthless - just to the contrary, this was done solely to favor the American offerings. Most of the concerns about liability are just marketting bs.

A friend of mine went out a bought a Turkish Mauser in 8mm. He did it before I could help him with his selection and his bore was just about washed out. His groups at 50 yds, even with good ammo were far too large for the rifle to be of any use as a hunter. But, at $50, he just brought it back, got half his money toward one with a crummier looking stock but a pristine bore and the darn thing shoots to an inch at 100yds. This is now his main sporter.

Please reconsider the expense of your M-N project ideas and consider putting your hard earned $ toward either another one or something else. Mikey.

saands · « **Reply #16 on:** March 21, 2003, 12:51:16 PM »

Thanks for the replies ... this really was just an idea for a project to keep me off the streets ... I wasn't trying to reclaim a M-N that I need to get back in service to put food on the table ... I already HAVE another M-N ... several it seems have snuck into the safe over the years ... I also have a few Mausers in various calibers and those were FUN projects ... and they're fun to shoot. I was just thinking that one of these M-44's that you can find so abundantly today could make for a fun project as well ... but maybe the magazine geometry just isn't conducive. Too bad ... as they can also be found with pre-1899 receivers which puts them in the same class as old lamps as far as paperwork goes ...

Thanks again,
Saands

hubel458 · « **Reply #17 on:** April 15, 2003, 03:34:30 PM »

As long as you have the others- do a 45-70 or 45-90 barrel.Get 45 cal
barrel with right threads.Open bolt face a few thousands, extractor will
work ok, just as it did for MN case.Little work on magazine.Big bore
shooting and reloading is the greatest.Get a 27-30 inch barrel.Ed.

gunnut69 · « **Reply #18 on:** April 16, 2003, 07:15:26 AM »

Hubel458 may have the answer. If your just in the search for a project then a 45-90(if the actions long enough) would be really neat. Brass is fairly cheap from Starline and the magazine could probably be made to work.. Goodn luck!!

hubel458 · « **Reply #19 on:** April 16, 2003, 09:18:16 AM »

Gunnnut-Saands--You can load up to modern pressures in a MN
for 45 cal stuff and brass lasts a long time.Huge selection of bullets
and bullet wts.350 0r 400 gr spitzer is great for deer and bear.Ed.