Breech-loading rifles increased the rate of fire to 8 to 10 rounds per minute with the additional advantage that they can be easily loaded from a prone, rather than standing, position, reducing the rifleman's visible cross section and thus vulnerability to counter-fire.

Ordnance Department requested prototypes of breech-loading weapons from arms manufacturers all over the world.

The rack-type system extractor was withdrawn automatically as the breech-block was opened and snapped back at the end of its stroke.

Approximately 5,000 Civil War Model 1861 rifled muskets were converted at the Springfield Armory in 1866.

The Model 1865 fired a rimfire .58-60-500 cartridge (.58 inch 500-grain (32 g) bullet, 60 grains (3.9 g) of black powder), the caliber matching that of the Civil War Minié ball, which was originally used in these rifles.