Any idea why the cavalry was still stuck with lousy muzzle loaders? And can you say what loading would have entailed, as in, how long it would take? I think I read upthread there is evidence the individual soldiers only got off about 6 rounds each which doesn't seem a lot in a twenty minute engagement. That's fewer than one every three minutes. Presumably, the last segment of the encounter did not involve much more than Indians bashing cavalry men's heads in so maybe the rate of fire was faster at the beginning. I would have wanted 6 Gatling guns.
The cavalry didn't have muzzle loaders. These are the Indians' weapons. The cavalry had single-shot 1873 Springfield rifles and Colt handguns
An experienced soldier could fire 12+ rounds a minute, not that you'd usually want them firing that fast. Each man carried 100 rounds, with more ammo available in the pack train. They were out there by themselves with no ready method of re-supply so the soldiers had to be mindful of ammunition usage.
I'm curious where you saw the estimate that the soldiers fired only 6 shots. The only hard evidence source would have had to been the dig but I don't know how they could estimate total shots fired. Many empty cartridges were picked up by visitors in the years afterwards.
Witnesses after the battle reported seeing piles of cartridges at some positions. I believe one said groups of 20-30 (caution: I could be wrong; I'm working from memory).
Maybe the best evidence for total shots fired is the sheer length of the battle. Custer was engaged for roughly 2 hours if you include the presumably light skirmishing that began in Medicine Tail Coulee immediately after Martin left with Custer's last message.
There were likely several "ends" to the battles, with the soldier positions at the south end collapsing first, then some time later, the group around Custer at the north end. The Indians fought from behind cover, raising up just long enough to fire. As the battle progressed and the Indian numbers swelled with late arrivals from the Reno fight, the Indians pressed forward to more aggressive and deadly positions.
At some point, one of two things (or both things) happened:
1) The soldier formation broke down and the men tried to make a dash on foot or horseback to one of the remaining soldier groups. This would have been the signal for the Indians to rush in to finish them off as they fled, exactly as they did against Reno. This is what I believe happened at Calhoun's position at the south end.
2) The return fire from the soldier position dwindled to the point that the Indians judged it was safe enough to rush in and finish them off. I don't think this would have happened as long as the soldiers were maintaining effective fire because the risk would have been too great. I think this is what happened on Custer Hill. Since there was no remaining soldier position to run to, they made a dash for Deep Ravine. It's hard to say whether the last soldiers fled because the Indians rushed in or the Indians rushed in because the last soldiers fled. I'm inclined to the latter.
Six Gatling guns would have been nice IF you could carry the needed ammunition and IF you could get them into action against a fast-moving enemy.