I’ve read a number of stories about why Custer’s attack failed.
One was due to archeological evidence showing that many troopers’ carbines were affected by continual jamming.
This led to a slower rate of fire and the Indians took advantage of this by moving in closer than they were earlier in the battle.
The decline in overall rate of fire apparently also rattled many of the troopers which could be noted by how separated they became from one another along Battle Ridge Hill.
This, of course, is only one possible scenario.
Hello Steve,
The “jamming” only concerned 1% or less of the regiment. It’s a myth.
The real cause of the failure of the attack was that Custer didn’t have his full regiment in the battle. He divided his forces to attack the Indians by front and flank, but the other columns, led by Major Reno and Captain Benteen, never joined him.
see http://www.custerwest.org