You probably have a Harrington & Richardson Double Action Hammerless- it matches the profile. These WERE available in nickel plate, but the trigger guard was usually blued, so yours is likely refinished. That IS the serial number on the guard. They were made in .32 S&W (6 shot) and .38 S&W (5 shot) Barrel appears to have been shortened (nicely) since shortest factory barrel was 3.25 inches. My references show only discontinued prior to 1942.
The downfall of the top break action- it was weak- and could not handle higher energy cartridges. These WERE well made little revolvers- not a Cadillac, but a decent Chevy. Unfortunately, the brand is poorly researched. Mr. Bill Goforth and a couple of experienced collectors had been researching them (Bill wrote the definitive book on Iver Johnson handguns), unfortunately, Mr. Goforth passed away before book was published (still waiting to see if it makes it out of the publisher's)
Cylinders on these are usually free wheeling until the gun is at the point of firing. .38 S&W is shorter, fatter, and less powerful than .38 Special- it DOES NOT interchange. If you remove the cylinder, you may find the serial number repeated on the underside of the top strap.
