Upgrading the bolt action 45/70

[grsjax]

I have an old Siamese Mauser rebarreled for 45/70. A great rifle and I have to add it does everything I want it to do. However being the tinker I am I can't help but think up things to do to perfectly good guns.

I got to thinking of ways to get more power from the gun with a minimum of gunsmithing. What I came up with is a possible wildcat cartridge that would require just rechambering the gun with no other changes. The cartridge would be based on the 50/90 2.5" brass. Turn the rim down to .608, cut an extractor groove in the base to create a semi-rimmed round and neck down to .458. This would give about a 20% increase in powder capacity depending on how long you make the neck. Looks like the magazine box is long enough for the bigger cartridge but might require some work on the feed lips.

Wonder if I could get a 500gr spitzer up to 3000fps

 

[rcmodel]

I'm not sure how much more then 45-70 high-end power I would trust a Siamese action with.

Consider, the unknown guy who heat-treated it probably died of old age 70+ years ago!

rcmodel

 

[grsjax]

Might just be simpler to see if I can chamber a 45/90.

 

[db_tanker]

why bother with the wildcat and just go with a 577/450 Martini Henry cartridge?

Dunno who makes the brass, but you could just get a neck sizer to form it up at 457-459 ID and then have a reamer made up from that loaded round? I say this as I do not know what true diameter that the 450 is, so I would form it up using a 459 cast. Mebbe get Lee to make you up a collet crimper and then go after some serious thump with the 500 grain jacketed...OR load up some that Beartooth would be proud of and use some 500 plus grain GC'd hard cast.

But hey, its your shoulder, not mine.

 

[rcmodel]

577/450 Martini Henry cartridge

That is some of the weakest brass ever made. Very unsuitable for the high-pressure loads grsjax is contemplating.

Personally, I don't know who would want more then you can get out of a 45-70.

It makes my head & shoulder hurt to think about getting kicked by one of the .458 WinMag wannabe loads you can put in a Siamese Mauser already.

rcmodel

 

[db_tanker]

RC,

I was actually thinking about him mebbe reforming off of the 577 Nitro express...but then I went and looked at the brass prices...um...yeah...


Forgo the wildcatting and just find your pain tolerance with what you got.

D

 

[roberto mervicini]

Re Siamese mauser strenght : even if the guy that heat treated die from old age 70 + years a go .... this action made in Japan is as strong if not stronger than a good german mause. This action could take anything that ruger # 1 could take.
By the way I am looking for one .....and a barrel in 45/70 or 458 mag 2" .
_______
roberto

 

[rcmodel]

is action made in Japan is as strong if not stronger than a good german Mauser.

Think that if you want, but you are wrong.

The Siamese Mauser is noted for being soft due to a different heat treatment then that used on the German made 98 Mauser at the time.

Frank De Hass, in his definitive book Bolt Action Rifles, lists it as being suitable & safe for cartridges not generating much over 45,000 PSI.
That includes the 45-70, .444 Marlin, 303 British, 7.62 Russian, 30-40 Krag, 348 Winchester, and several wildcats that develop similar pressure.

rc

 

[roberto mervicini]

If we are talking of Siamese Mauser model 46 this gun is not made in germany but made by Tokyo Arsenal in Japan .
______
roberto

 

[rcmodel]

Yes, that's the one I am talking about, and thats what I said.

Had it been made in Germany, it would be stronger due to better heat treatment and probably better steel to start with.

Japan was still not too far removed from making match-locks at that time.
They still had a lot to learn about steel & heat treating then.

rc