Just to add to the information, the Arsenal ammunition was copper cased, not brass. The copper expanded on firing, but unlike brass, did not shrink away from the chamber walls. The copper case clung tightly to the chamber and this is what caused the extractor to rip through the rim. The lack of a cleaning rod compounded the error.Actually the Indians were adept at reloading rim fire ammo without tools. About 35 years ago, a prairie fire burned the battle field and many shell cases were found and indicated different skirmish lines than had been previously thought. One of the discoveries was rim fire ammo with evidence that the rims had been indented and bent out again for reloading. A old nail with a head could be used to bend out the indentations on the case rim. One professor used the heads of old fashioned matches mixed in a slurry, a few drops placed in each rim fire case and set in the sun to dry. Then the cases filled with powder and a round ball thumbed in the end. Some of the cases appeared to have been refired a half dozen times.
In addition, Custer's men still had trapdoor rifles and balloon head ammo. The sloppy chambers of the trapdoors would cake with powder fouling and the cases would stick and the extractor would tear the balloon head rim with out extracting the shell. The same difficulty was noted ten years earlier at the wagon box fight and in Africa by the Brits with Martini Enfields in the Anglo Zulu wars. After five to seven shots the guns had to be chamber cleaned to keep functioning.
I have two trapdoor rifle, an 1866 (50-70) and a 45-70 (1873), with modern brass, neither jams no matter how fast you load and fire.