Check to see if the barrel flat above the extractor has the same number as the cylinder. That year production should have numbers on most of the parts. If it does not match it could have been a 38 S&W cut to use 38 Specials and rebarreled. Be careful if you choose to polish the cylinder not to exit the cylinder front and round off the edge of the cylinder. This has to have a flat surface at the barrel throat to maintain accuracy. One other idea is to use a cylinder brush with bronze wool wet with Hopps #9 to clean the cylinder . Good luck