Good catch on the serial number. Frontiers are in 44-40 caliber, but serial numbers stop at 2072 acording to Roy Jinks book. I would suspect it may be a 44 Russian caliber. Barrel is cut, most likely from an original 6" or longer barrel.

The trigger guard on S&W Russian Models are perfectly oval and if the spur is removed, the shape will look exactly as non-spur trigger guards. That feature remains a mystery.

__________________
Gary
SWCA 2515