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Swedish M1867 Rolling Block

12.7x44R (12.17x44R) to .50-70 Government Conversion



I have a Swedish M1867 Rolling Block that was originally in 12.7x44R and you cannot find any brass for that caliber. My rifle had been “sporterized” sometime in the late 1800’s so it isn’t original and making a conversion really wouldn’t affect its value but to me, in my humble opinion, it would actually increase its value as well as utility.

12.7x44R Brass can be made from 50-70 Government, 50 Alaskan, or 348 Winchester brass but you’ll find that the rim will have to be reduced in diameter, length changed, and in some cases the cartridge base in front of the rim will need to be reduced in diameter also. The 50-70 brass appeared to me to be the best to base my conversion on and I found that Bertram brass rims are too thick and Starline brass the best choice because they are consistent in dimension and the closest match the 50-70 specs.

A little History:

Apparently the 12.17x42R RF was a modification by Sweden and Norway of the .50-70 Government cartridge which had been adopted by the US Government in 1866. The cartridge went by several names that I have found during my research:




12.17 x 44 R Norwegian Remington

12.7 x 44 R Norwegian Remington
.50 Norwegian

.50 Norwegian Remington

12.7 x 42 R Swedish Remington CF

12 x 44 R Swedish Remington CF

12.17 x 42 R Swedish Remington

12.17 x 44 R Swedish Remington

12.7 x 44 R Swedish Remington

12.7 x 44 R Swedish 1867

.50 Swedish Remington

12mm Remington 

12 x 44 R Remington 

12.7 x 44 R Remington

DWM 17 144

GR 497(H) 

SAA 8815

When adopted by Sweden and Norway in 1867, the case was 42mm long and then in April of 1871 it was changed to 44mm so the black powder load could be increased due to an increase in the projectile weight by Norway. There was apparently no change made to the rifle’s chamber in either country because the chambers would accept the new cartridge.

Why Norway and Sweden decided to change the 50-70 dimensions to 12.17x42R is a mystery. They purchased all rifle and cartridge production machinery from Remington and changing the tooling for a different cartridge must have cost more than if they had simply adopted the 50-70. As you’ll see below, the dimension differences are very small and from what I have read, the performance of the 12.17x42R was not up to the level of the 50-70.

The 12.17x42mm Cartridge:


The 12.7x44mm Cartridge:

12.7mm Projectiles: French drawing of the Swedish 12.7mm bullet dated 1 December 1901

French drawing of the Swedish 12.7mm bullet dated 11 December 1903

50-70 Government aka 50-70-450


12.17x44R and 50-70 Government Comparison:

Here is a comparison of the basic dimensions based on the 1 April 1871 12.17x44R Drawing:



12.7x44R *

 .50-70 Government  (vs 12.17x44R)

Case Length:                                   

13.9 Linje=43.604mm=1.717”

 1.75”  (+0.033")

Rim Diameter:                          5.11 Linje=16.03mm=0.631” 0.660” (+0.029")
Rim Thickness:                       0.52 Linje=1.631mm =0.064”  0.065” (+0.001")

Overall Length:

18.2 Linje=57.09mm=2.25” 2.25”  (+/- 0)
Bullet Length                           7.55 Linje=23.68mm=0.932” 0.965” (+0.033")
Bullet Diameter                                4.021 Linje=12.61mm=0.497”  0.515” (+0.018")
Bullet Weight 425gr 450gr  (+25gr)


13mm (0.512”) **                              0.520” (+0.008")
Lands 12.42mm (0.489”) **

0.5”    (+0.011")

* Approximate because at the time of adoption, 1 April 1871, Sweden and Norway used a unit of measure called “Linje” or Decimal Lines. To add to the confusion, Sweden used a different value for a “Linje” and Norway another. The conversions of dimensions shown above are as close as I have been able to determine so the numbers are approximate metric values.

**Actual measurements of two Swedish rifle bores

As a side note, Norway started adopting the metric system in 1875 and Sweden 1876.


Drawing from actual measurements of two Swedish rifle bores


I’ve never found an original drawing of the 12.7x42 or 44R cartridge in metric units and if anyone has one then I would love to get a copy.


Above is a photo of the rifle prior to the conversion. Note that barrel has been shortened as well as the forearm. I have removed the really cheap front and rear sights that were soldered to the barrel as well as the front sling loop. I’ll be replacing them with something of a better quality but still with a “period” look. Eventually the stock and forearm will also be replaced but that’s a project for another day.

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