Maybe if it was a .45 you could assume that but I wouldn't think that would happen with the reduced bullet diameter of a 38-40. I think he's gotten some slightly oversized bullets. Maybe he will reply soon and help us solve the mystery.
Abilene chimed in while I was responding to Sir Charles. I read the sass comments but he doesn't say that he actually mic'ed the bullets he's using just that he's 'using' .401 bullets. Its got to be his ammo thats the problem to be an issue for two completely different rifles, an original winchester and a modern copy.
Reread his sass thread and in one of his replies he says that he gets a ring of lead when crimping, that tells me that he is still seating the bullet after he's crimped the case. This would put lead on the outside of the case and easily leave it in the chamber when the gun is fired. He needs to adjust his die.