Could use some help with this one

[Danth]

A close friend and very good gunsmith passed away and left me some of his stuff. Amongst the barrels was a barrel I thought might be a 7X61 S&H as he was a fan of this cartridge. I recently examined it and find it's not, but cannot figure out what it is. It's belted with the dimensions of the 7x61, but it's only 2.155" long with a long shoulder like a 300 H&H. I thought it might be a short chambered barrel for some other caliber, but I came across his dies for this cartridge. The barrel and dies are not marked. The dies have very fine knurling and both the top and bottom of the dies are chrome plated. I can find no information an a cartridge with these dimensions. Any ideas?

[cwtebay]

Would it be possible to cast the chamber with Cerro safe? Or if you have a sized case, post pictures of it with measurements such as in the photo I attached.

I'm sorry that you lost your friend.

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[NyFirefighter357]

IDK but this is what I found

https://www.google.com/search?client...&q=7X61+belted

https://en.wikipedia.org/wiki/7%C3%9...harpe_%26_Hart

https://www.chuckhawks.com/7x61_SH_Mag.htm

[Danth]

Yes, though some of the measurements are close, this is definitely not 7x61 S&H. The length is only 2.155" and the width at point "D" is .502". It's shorter and "fatter" than 7x61 S&H

[cwtebay]

It sure sounds like a straight up 7mm Remington Magnum.
The case length is right, your description of the shoulder is not though.

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[Winger Ed.]

Most gunsmiths are pretty reasonable with doing a chamber casting.
I had it done on a mystery rifle several years ago, and it didn't cost much.

[Danth]

yup, done a chamber cast and sized casing, that's how I came up with the measurements.

[cwtebay]

yup, done a chamber cast and sized casing, that's how I came up with the measurements.

Could you post the rest of your measurements?

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[Danth]

A-530
B-510
C-44 deg
D-502
E-303
F-1.520
G-1.875
H-2.155

[Landy88]

Your measurements are close enough to, maybe, be the 7mm-350RM wildcat. Back when it was the only short magnum it was catted from 6mm to .416.

Two Brit belted .275 existed but both were much longer; and one was skinnier, too, being in that odd belted .473 diameter case family.

[Danth]

Landy88, think you may have hit it. Only area of concern is the shoulder angle/length. Having read up on 7mm-350RM, don't think I'm going ahead with the build. Doesn't sound like an efficient cartridge, and forming cases is a real task. Thanks much to all

[Landy88]

Was your friend old enough to have beaten Remington to the first short magnum?

This mayn't have been derivative. The shoulder differences could be because it's his own original cartridge.

[Danth]

Wow, hadn't thought of that possibility. I'm sure this was made in the early 50's when he got out of gunsmithing school. I finally have a good procedure worked out to produce good cases with minimal waste. This is basically a shortened 300 H&H, necked to 7mm. As you say, approximately a 7mm-350RM. Time for more research: as the 7mm-350RM was overbore, would this version with a slightly smaller volume help with the overbore issue? Also, do the larger weight bullets utilizing less powder help?

[Landy88]

It seems that he beat Remington to the short magnum and Winchester to the .284. His should be a fine round in a rifle length barrel.

The only thing that doesn't work well with Rem's 6.5 or the smaller bore .350RM Wildcats is trying to stuff them in carbines. As good as it is in .350, the light magnum carbine is a specific midbore niche. Smallbores underperform, and bigbores are deadly from both ends.