ChuckO, If you are sure on the serial number, (61500-66999) it sounds like someone either rebuilt that gun, or a left over New Police frame was built later by Colt as a new Police Positive. If it were in fact a New Police revolver as marked on the frame, it would have been made in 32 Long or short Colt. The cylinder throats should read .320, in fact, you should be able to load a 32 Colt Long Cartridge into either end of the cylinder--the charge hole was simply a .320 straight hole bored end to end. The gun probably was rebarreled and a new cylinder installed at a later date when the difficulty of obtaining ammunition became burdensome. The 1926 patent date suggests this. Also, I have only seen the B 32 marking on guns made in the 30's.