According to exhaustive archaeological research at the Custer Battlefield site, the most common weapons used by the Indian tribes were, in order of number, .44 caliber Henry repeaters, .50 caliber Sharps, Winchester '73s in .44-40, Springfield's Muzzleloading Trade Muskets in various calibers, and an eclectic collection of other firearms, including Smith and Wesson .44s, Spencer rifles, and one Forehand and Wadsworth .32 revolver.
Even though 25-30% of the Indian warriors had repeating rifles, the most telling weapon on the battlefield that day in 1876 was the bow and arrow. It was the combination of mass flights of arrows, backed with the rapid-fire Henrys, that such a devastating effect on the 7th Calvary.
How did the Allied Indian tribes get their Henry rifles? Interesting question. The Western traders solemnly swore to military investigators in 1876, that they never sold or traded Henry or other repeaters to the Indians. The Army and Navy journal of that year suggested, sarcastically, that perhaps Winchester should go after the Indian tribes for patent infringement- since no one would admit to providing the rifles, the Indians must be manufacturing the rifles themselves.
After the battle, General George Crook noted that the Sioux warriors were more effective on horseback with bows and arrows, rather than the single-shot trade muskets. But he added, when the Sioux came into possession of the breech-loader and metallic cartridge, which allowed them to load and fire from a horse with perfect ease, they became at once 10,000 times more formidable.