It appears to be a five inch barrel, which means it started out as a .38S&W caliber ( 38/200) made for the Brits as a lend lease gun. It's had heavy buffing and the nickel finish was applies to everything metal, it looks like, including the trigger & hammer. No case colors visible on them. You don't state the caliber that you have been shooting in it. It is probably .38S&W Special, right? Which means the cylinder has been reamed out to accept the .38 Special rouns, but the barrel is still .38S&W caliber. It was probably shipped to the Hartford Ornance depot, for the British, in Sept 1942, or thereabouts. It's not a collectable so value is as a shooter only, or about $150.