There's little doubt about this being the real deal.  The pistol is in the kind of condition that you find most Indian used weapons. Surprisingly, it still functions most of the time.  It's got a weak hand spring so sometimes the cylinder needs a little help to rotate completely.  I believe the holster is made from Buffalo hide.  There's a similar Remington pistol on page 82 of  "Custer Battle Guns" by John S. duMont that was found at Rosebud Creek. The Indians used captured guns from the Battle of Rosebud at the Little Big Horn. Would display nicely in any Custer Collection.  
Sold