Hello,
Curious as if anyone would know whats involved in converting a Mosin Nagant to a .300 Win Mag. What changes have to be made.
Thanks, HeeHaw

I have converted one to 45/70.
I had to grind a special tool for opening up the bolt face.
It is not like a Mauser, in that the barrel must be relieved for the extractor.
picture of the rifle

picture of me cutting the extractor relief on the breech of the barrel
picture of cutting threads and shoulder

picture of cut off, extended, and welded on bolt handles to clear AR15 Riser scope mounts

more breech milling

Nice pictures Clark, thanks for sharing.

Scott

How hard and expensive would it be to simply rebarrel it without changing the caliber? I have one that I got for christmas but the barrel is really shot out. I like that it has "1942" stamped on the top of the receiver, but I'd like it even more if it would hold at least 3" groups at 100yds. It scatters them pretty good as it is, especially with the cheap mil surp ammo.

Ian

12FLVSS,
To rebarrel in 7.62x54 or anything with a case head that size or slightly smaller, one would only have to:
1) Thread the barrel
2) Cut the shoulder
3) chamber
4) headspace
5) Cut extractor relief

It might be easier to get one off another gun or just buy a new gun:

1) It is fairly easy to find an M44 with a good barrel.
2) It is very easy to find an M39 with a nice barrel.
3) I found a 91/30 with a minty barrel, but they are very hard to find.


I know a guy with a sewer pipe barreled 91/30 that shoots sub moa groups at 100m. I would not believe it if I had not seen it. The worst barrel you would see in looking at 200 barrels at the gun show, but it gets great groups.

That guy makes his own scope mounts with Williams over center scope rings.
PIc of home made 91/30 scope mount with bath tub anodizing job

I'm not sure exactly what I have here... can you tell from the photo?

Clark,
Thanks for responding . Will see what my friend can do from your list of choices for modifying my Mosin.
Thanks, HeeHaw (Dennis)

That looks like a 91/30 to me.

91/30s for sale at AIM Surplus

Covert it to 300 winmag huh.... hmmm... it would take lots of faith.





My rifle would shoot no better that chest sized groups @ 100 yards for years. I just accepted the fact that that's what this old war horse with warn barrel would do and didnt shoot it often. One day I ran out of the large batch of ammo I'd picked up when I first bought the rifle. I then picked up more surplus ammo... friend then took it and fire MOA groups with it using the battle sights.



So Im saying, try some other ammo before writing it off.

thanks Clark, that package is exactly what I got with mine. All the little bits and pieces are the same.

Ian

Cas,
Looking at the base dimention of the 7.62x54 R case at .485" and the 300 Win mag at .513", the chamber walls are not going to get thin enough to be a problem.
I can increase the load until the bolt sticks with the 7.62x54R cartridge, and I am sure one could do the same with the 300 win mag.

The question I would have is, "Why trade a repeater for a single shot, just to get 200 fps?"

http://www.reloadbench.com/cartspec.html

My worry would be from a questionable old action, made to take loads that average 45,000 PSi and putting in a cartridge that averages 54-64,000PSI. Sounds like the makings of a bomb depending on when the gun was made. My mid WWII production rifle is kinda scary looking anyway, and I used to question the safety of standard loads in it.

Sure you could download it to 7.62x54R levels..... but why?

Cas,
Never thought about the difference in pressures.
Guess I'll just leave it alone .
Just a basic Remington Armory 1917 with a hex receiver and a worn barrel.
Just was curious as to what may be involved to convert a military weapon.
Thanks for your time and input.
HeeHaw( Dennis )

Being an old Remington, it may be worth more as it is.

I couldn't tell you about 2 & 3, but as far as #1 goes, I'd never presume to know more than the people who designed it.

I have not designed any guns that went to production, but my father has, and I stood around and watched.

I HAVE been designing things for 25 years, and it is like laws and sausage being made. You don't want to see what goes into it.

My favorite phrase from mangagment to engineers at the start of a design is, "This time we are going to design something so there are no follow on problems. By the way, we need working prototypes in 2 weeks."

I intend to make a 338 Lapua magnum on a 91/30 action, but it will be a single shot, like the 45/70 I made on a 91/30. It will not be working in 2 weeks. This week I am removing the barrels and drilling and tapping 9 of my VZ24s.