Archaeological studies show that only 9 to 10 rifles had problems - and there were 647 rifles.
Everything else I said is true. They died of Custer’s miscalculation of the enemy forces and some bad management decisions, including how Custer related to his officers.
Underestimating the enemy is always a bad thing.
Getting seriously outflanked is also a bad thing.
Doing it when undermanned in an indefensible location is a bad thing too...