After the end of the Civil War, the Army started to convert the remaining muzzle loading rifles to breech loaders based on the design by Erskine Allin, who was the Master Armorer at Springfield Arsenal. These conversions were the .58 cal Musket M1865 Trapdoor Allin Conversion, of which 5,000 were ordered by the Union Army. While this was in process, the action was further simplified and this improved design became known as the M1866 rifle that was chambered in the newly designed .50 cal rifle loaded with 70gr. of powder. The introduction of the self-contained metallic cartridge case also led to a reduction in bullet diameter where smaller diameter bullets and grooved barrels led to a huge improvement in accuracy. This was a trend followed by European nations as well with the British moving from .577 cal muzzle loaders to Snider conversions and in the 1870’s reducing the caliber to .45cal. with the introduction of the 45 Gatling and Gardener and the eventual adoption of the 577/450 Martini Henry, as well as the French who progressed from large caliber muzzle loaders to the 11mm Gras conversions.
Copper case with a tinned iron bar (magnetic) anvil crimped into the case holding the priming against the case head. This was the priming system used from October 1866 to March 1868.
Copper Benet primed case with the .197” crimp above the case head. This was the service cartridge between December 1871 and January 1872.
Martin primed case with re-entrant fold at the rim. These were manufactured by Union Metallic Cartridge Co. of Bridgeport, Conn. and was manufactured between November and December 1871. See also Hoyem Vol. 2 p. 50
The rounded head with no headstamp might be either Remington or US Cartridge Company, but without proof from the box this round was in originally, it is speculation only.
Farrington Primer, which was a distinctive style of primer that was patented in 1872 by DeWitt Farrington and used by the U.S. Cartridge Company.
1. Bertrams Australia
2. Connecticut Cartridge Corporation
3. Chicagoland International Cartridge Show, The GM is for George Murphy
4. Dominion Canada
5. Dixie Gun Works
6. Dixie Gun Works
7. Old Reliable
8. Winchester, March 1889
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