The U.S. Model 1866 50 Government centerfire caliber (50-70) is also known as the second Allin conversion. It is the first of the centerfire trapdoor rifles. 25,000 were manufactured in 1866 by Springfield Armory from altered Model 1863 percussion muskets. The 40"" round barrel has an excellent bore with bright, strong rifling. The barrel, bands, triggerguard, and buttplate are bright. The breechblock, which has 1866 over eagle marking, retains its original dark quenched color. The lock and hammer show traces of their case colors but have mostly turned. The stock is very good with sharp edges, a couple of nicks along the ramrod channel, and scattered issue dents and dings. There are two light cartouches on the left flat. The action functions correctly. The Model 1866 was the first trapdoor rifle to be used in combat at the August 1867, Wagon Box fight near Fort Phil Kearny, WY, and at the Hayfield fight near Fort C.F. Smith, MT, both as a part of the Red Cloud War. This Model 1866 is far above average condition for one of these rifles.