I have a Ruger GP-100, where one chamber in the cylinder refuses to release the brass. It is also more snug than the other chambers when inserting spent brass, but accepts unfired bullets easily. Gave it a cleaning with no change. Could clean again. Advice? Tried cleaning chamber w/ brass brush, patch, solvent. Have not tried any special lead removal chemistry. Gun was used when acquired. I have put about 100 rounds through, max. all 38sp. some +P. Thanks in advance.