12.7x44R Rimfire

This is Jeff at RCC Brass and we are making a 12.7x44R rimfire for a customer and I’m seeking a dimensional drawing for this cartridge. We are not making an actual rimfire case, but we are offsetting the primer pocket to the side of the case. Then they are using a 22 blank as the primer.

Anyway, if anyone has the dimension they would like to share, it will be greatly appreciated.


For this to work you need to know that all measurements are in Norwegian lines. And after 1815 (i think!) the Norwegians went decimal instead of deviding by 12.
A Norwegian inch is a foot (31,4cm) devided by 10 and 1 line is an inch (3,14cm) devided by 10 ie. 0,314cm or 3,14mm.

So a Norwegian line is 0.1236 US inch

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This is in mm!


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There’s some drawings and meassurements in mm. of the chamber, in this thread. The original norwegian and swedish 12mm Remington cartridge was 42 mm. long. Norway upgraded it’s cartridge with a new bullet and more powder in 1871. The new cartridge was 44mm.

I have aquired a little more knowledge about the decimal system.

It seems that gunmakers and mashinists devised the decimal inch system in the 1820’s and it existed parallel to the old system until exchanged for metric in 1875.

By law of 1824 the Norwegian inch was revised to 3,1375cm and a line to 3,1375mm

Wich means that a decimal line on the drawing equals US 0.12352"

Jeff, the drawing shown so far is for the 12x42R Norwegian RF. What you requested is a drawing of the 12x44R RF. I have a copy of the official 1871 12x44R RF drawing, and tried to post it, but was unable to figure out how to do it. The dimensions you need are the following: Rim diameter 16.03mm, base diameter 13.96mm, mouth diameter 13.20mm, rim thickness 1.63mm and total case length 43.60mm. The correct bullet diameter is max 12.60mm, so the internal case mouth would have to be the same.
Please note that the 12mm RF cartridges were not 12.7mm. This converts to .50 caliber, but both the rimfire and centerfire versions have nothing to do with .50 caliber. The RF cartridges were called “4 line copper cartridges” until 1879, after Norway converted to the metric system in 1875. In Norway the centerfire 12x44R were usually called 12mm, whereas in Sweden and Germany they were called 12.7mm.

Thank you, this has really been helpful.

Jeff Roberson



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