The MN will handle a 45/70, particularly if you're not handloading. I would imagine so long as you stay within the pressure limits of the 7.62x54r (~40,000 CUP, but I don't quite remember. Don't have load manual handy either or else I'd look it up for you.) I think you'll be fine. I believe Clark, one of the regulars here, has done this conversion before. You may wish to speak with him about it.

The question is: how much experience do you have doing machine work and gunsmithing. And, how much work are you willing to put into a Mosin-Nagant? From everything I've read about this conversion, it is not an easy one.

on third thought, and why it might not be done yet, this would also make a NEATO platform for a 405 win.

jeffe

I read about a MN one fellow recently converted to .444 Marlin. Used a Winchester barrel and put it in a MN sporter stock from GPC. Said it made for a mighty big handfull in .444. I'd imagine a .405 would kick even harder.

Personally, I've got a mannlicher type project lined up for a MN sooner or later. I think that if I could find one that was accurate enough, a bolt job, new sights, and full length stock would make one fine open sighted hunting rifle. But its like everything else; I've got way too many other projects in line first.

I picked up a polish nagant with the intent of making a 480 carbine as a companion to my revolver. A friend advised that the magazine would be a major headache, but I didn't listen to him before picking up the rifle. He was correct, to the rifle sits in the back of the case.

If you can live with a single shot, it'll be fine, if you want a repeater, you'd have to essentially fabricate one yourself, or cut and weld a siamese mauser magazene to the nagant floorplate. That is where all the work is, slapping a barrel on is a no brainer.

Here are my 45/70 Mosin Nagant pictures.


45/70 with Shilen barrel blank on Polish M44 stock, with scope, it weighs 17 pounds, and still kicks like mule.
http://www.thehighroad.org/attachment.php?s=&postid=127760
Cutting threads and measuring distance to shoulder on 91/30 cutting threads
http://www.roderuscustom.tzo.com/cgi-bin/ib3/iB_html/uploads/post-3-08809-rebarrel91_30small.jpg
milling vertical for 452/70 extractor relief on breech
http://www.thehighroad.org/attachment.php?s=&postid=126137
milling 45 degrees
http://www.thehighroad.org/attachment.php?s=&postid=126141
2 91/30s sporterized
http://www.thehighroad.org/attachment.php?s=&postid=135114
Glass bedding 91/30 with two pillars and tape under sear to decrease trigger spring
http://www.thehighroad.org/attachment.php?s=&postid=926374

91/30 recievers older than 1942 have inner "C" ring, and I think are better.

I had to grind a special little lathe tool to open the bolt face.

--
Be careful what you pray for, it can happen.

A thing of beauty is truly a joy to behold.

Thanks,

Hey everyone, thanks for the insight. I am going to do some more digging with measurements etc. Sorry I didn't get back into the forum for a bit - been busy making my wife's birthday present. Anywho....

I have a Mosin-Nagant of 1938 vintage with a sewer pipe for a bbl. After reading everyones input I think I am going to follow thru with the conversion. There is only one concern that is lurking in the back of my head - that being the strength of the MN action. Obviously staying within the pressure that the action is/was designed for is the prudent guideline to follow. Is seems to me there would be more bolt thrust from the 45/70 than with the 7.62x54R round. I may be totally wrong here...dunno. That is why I am asking the question.

Assuming there is more bolt thrust, what would be the prudent level of a load before you start moving into the zone of problems? If I am all wet in my assumption then there shouldn't be an issue. I would not pass the "Lever action" load data in any gun. This is just my personal level of recoil tolerance - irregardless of whether the gun can take it or not. If anyone has thoughts on this, please give me shot back with em'
Thanks
Eric

With 50 gr IMR4895 and 180 gr Sierra in 7.62x54R, the bolt of a 91/30 will get sticky.



Do you know how much pressure it takes to get sticky one of those rimmed cases in a bolt gun?



Can you imagine the recoil in with a 45/70 that approached that level of bolt thrust?

someone tell me the case head size of both...


the 50 gr load is nearly 60,000 psi, or 4000 over max saami for a 7,62... so, imho, an overload is an overload...

jeffe

Guys,

No question or argument on overload issues.
Overload is OVERLOAD - gas dumps and the such aren't fun - I KNOW from personal experience! Nearly lost my right eye to a gas dump. I now have a synthetic lens to proove it.

My concern is the 45/70 standard type loadings in the 25K CUP MAX range...what does the MN action respond with? Lug setback? Action flex - grenade type explosion?...etc...?

Knowing that most of the original mauser cartridges in the original actions were designed for less than 50K CUP, this gives a guy a level of comfort and repectable guideline in conversion. I am not sure of the MN type actions' max capable sustained level of pressure without failure. I have no interest in pushing the envelope with a conversion with a MN action.

I have experienced "overload" with a MN action. I have a customized MN with a .308 bore BBL. Thinking I was dealing with a standard military bbl that had been turned to the contour it was - I didn't think that military surplus ammo would be a big deal. (BAD mistake - should have slugged the BBL - chalk another one up to the grace of GOD!) Standard military surplus ammo resulted in a massive felt recoil - bent extractor, and the need to tap the welded steel case out of the chamber with a cleaning rod. In the end I got the crap scared out of me again.......

I am not interested in making a questionable conversion. If you guys have knowledge of the pressure limits of the MN actions and whether the 45/70 conversion is a reasonable endeavor - I am VERY interested in learning more.

Sorry to rant -
Eric

Eric,
I don't know how else I can communicate with you.
I have converted a 91/30 to 45/70.
I have shot 60 gr of Re7 230 gr again and again and again. That is 27,000 psi, and nothing like the 80,000 psi I have shot in 7.62x54R in the same kind of actions.
There is no setback.
It weighs 17 pounds and kicks like a mule.

Clark,

Thanks for the insight. You communicated just perfect - sometimes I am a little "hard of reading (hearing)". I do appreciate your input whole heartedly. Honestly, I can't see a MN action having trouble with the pressure either. I have been talking on another forum about this very conversion - The collective response has been positive. There are a few out there that do not have anything nice to say about MN conversion - or the actions in general. Oh Well, to each his own.

While the board has been down, I have learned alot bouncing around on other forums. I caught up with a guy who has done the 45/70 conversion to a MN, MAS Bolt gun, and a M95 I believe.....all of the conversions worked fine. One interesting post was that the MN bbl threads are the same as a Ruger? This sounded pretty interesting, would make bbl work pretty easy. I do not know if this is true or not - or what make and model of Ruger bbl is interchangeable.

I am adding this conversion to my list of projects - we'll see if I can make it work with the action I have. Can I bug you for particulars if I run into a snag?
Thanks again
Eric

clark, you are way over sierra's reloading book. it list max for imr 4895 as 45.1 grains.


steve

Eric,

When you want, I can photo the tool I ground to open the bolt face inside of the shroud.



Steve,

I like the Sierra manual, but my choice is 47 gr for my accuracy load. Going to 50 gr was just to see what would happen. I did that once for a point of reference. I like to stay 6% below sticky bolts.

Clark,

Thanks for the offer on the photo - Would be most interested! I was mullin over the other needed "opening up" problems on the action. The mag rails need to be opened up a bit, maybe a little adjustment to the feed ramp - can't see really much more other than polishing, etc.
Would love to have a copy of the equipment that works for the job on the bolt.
Thanks again
Eric