Do you mean in the cylinders of your revolvers? Using a shorter case in the longer chamber (38/357) will usually lead to some serious carbon build up in the front part of the chamber which can be difficult to remove, and may make it difficult or impossible to chamber full length rounds. The best solvent I've found for that has been M Pro 7, but there is still a lot of work involved. An over size brass brush chucked into your electric drill can speed things up some. Best bet is to use 357 brass and eliminate the problem.