Something that could be the culprit that i haven't seen mentioned is the barrel flange could be interfering with the frame on the bottom of the chamber area in the front of the pistol? This is more likely to happen than one might think? It is very close tolerance and can be checked for very easily... best, til...lat'r....GT...
BTW, this is also the area that receives the most deformation during re-barreling and it could be a result of that type of operation?...
BTW squared, remember what I recently said about the cure being as far away from the problem as you can get! This could be one of those!!!