I had that exact thing on my 357 Mtn Gun. The bushing had backed out so when the round was fired, the primer would back out, filling the hole and would actually jam the gun. I think that is why the guy I purchased it from sold me the gun in the first place! I sent it in to S&W and had it repaired. I later traded it to a friend for a 696 ND .44sp. The gun was fine after repair.