All points well made and well taken! Sure, there were experienced veteran soldiers, especially in the NCO and Officer corps. But with only some exceptions, their battle experience was most likely from the CW. The average private was lucky to be able to hit the side of a hill with his hard-kicking Springfield Carbine, let alone be any kind of marksman. (Farmers, of course, might have done some hunting, but certainly not all of them.) Of course, the troops were given "unlimited" target practice. Per regulations they were allowed a total of three rounds of .45-55 ammo per man per month! Where their officers even regarded target practice as useful prior to the LBH debacle, and in the few instances where a few .50-70 Sharps Carbines or M1868 Springfield Rifle Muskets ("Long Toms") were available to supplement practice and provide for foraging in garrison, the troopers might be a bit better shots. (Companies C, G and I, 3rd Cav, stationed at Sidney Barracks, NE, were blessed with 5 Sharps carbines and about 50,000 rounds of .50-70 ammo. This probably stood them in good stead at the Rosebud Battle, on 17 Jun '76, but no records or reports of the effectiveness of the average trooper are mentioned in the after-action reports of Capt. Fred Van Vliet, 1Lt Emmett Crawford, or Capt. Andrews. At least their troops mostly survived.
We can thrash and rehash the LBH battle from now until the sun goes supernova, and the facts will remain: Custer's troops ran into a superior enemy force that was actually reacting to his attack, were isolated and cut up in detail. Where his other battalions attained a good defensive position (after getting badly cut up when their original attack failed), they survived, albeit with heavy casualties.