Converting a 12.7x44R (CF) to .50 Government

Started by 762x51, 26. April 2015 kl. 11:45:09

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What are your opinions regarding changing the chamber of a rifle from 12.7x44R (CF) to .50 Government (.50-70 or .50-70 Sharps)?

My rolling block was made a "sporter" by cutting the barrel to 30 inches, removing the original sights, soldering cheap sights to the barrel, soldering a cheap sling swivel to the bottom of the barrel, and cutting the forearm. As you can see it has no "historical" value so changing the chamber would probably increase it's value. :-)


Why would you want to change it to 50-70?


Hi John,

When I first got the rifle it appeared that making 12.7x44R(D) ammo was going to be a problem but I have since changed my mind and will be leaving it as-is. No need to reinvent the wheel, so to speak... ;-)



There is no problem making shots for 12,7x44 have make many



Would you mind posting details of the cartridge you make?
Which case do you use, the bullet, powder, and charge?


Mårten Wigardt


I went out on a limb and bought one (1) shell case in 50-70 government just for the hell of it. I tried it and it chambered beautifully in BOTH my 12.7 Swedish RB's. One is Husqvarna and the other is Carl Gustaf. The only trouble was the rim. I bought 100 more shells and put them all in the 13 mm chuck of my power drill (again a very snug and nice fit), used a file and shaved the rim down to exactly 16 mm. Then I put them through my Lee loading equipment, with greased bullets and roughly 60 gn of powder.

I now have no trouble hitting the bottom of a Red Bull can (50 mm diameter) can at 50 meters and I haven't had a single cartridge refusing to chamber, although a few have required a little thumb assistance. It's a tight but easy fit, absolutely no gas leakage between shell and chamber. Neither of these rifles have been re-chambered and one of them is in pristine condition. All I did was take a little brass off the rim.

I used Starline 50-70 govt. brass as I don't know of any other. But in my experience these shells are far superior to the horribly expensive (3 to 1) Bertram Brass shells I originally bought. Also, the Starline shell won't buckle as easily as the BB shell.

I'm still surprised it worked since most testimonials have been to the contrary and recommending the arduous task of fireforming 348's.


Hi Mårten,

Thanks for the update and glad to hear that the 50-70 cases worked. A friend had sent me a fired case and it wouldn't chamber in either of mine and I think that's because it was fired in a rifle chambered in 50-70 which is a little loser chamber.

I found 85 cases on one of the for sale boards along with a set of Lyman dies and they should be here this week. It was a gamble but if they wouldn't work then I was going to rent a 50-70 chamber reamer and re-chamber one of mine that's a "sporter" and really doesn't have any collector value. Like you, I didn't want to go through having to convert brass to get it to work.

I have a collet chuck on my lathe and a .5 inch (12.7mm) collet should work to hold the brass and reducing the rim will be simple with the lathe.

What mold are you using for your bullets?


Mårten Wigardt

I use a specially ordered steel mould from a Danish company, took 4 tries to get it right. The bullet is a 450 grain minié type with 5 grease groves. I'm going to put a cardboard/grease cookie in my next batch to see how that affects precision and if it facilitates cleaning. I'm a bit concerned as to how this will affect the hollow base expansion. But that's what black powder is all about, isn't it? Trial and error and trying not to blow oneself up.

Paul Pelletier

how can I get the same mold from the Danish company where you got your mold ?