If it is not stamped Smith & Wesson on the top of the barrel (along with a string of patent dates), and there is no logo on the left frame, it may be a copy. The other possibility is that the refinish removed all the stampings, which is difficult but not impossible to do. As Mike said, it appears to be a Perfected-type gun; most of these had a top and side cylinder latch, but yours does not have the latter. Many copies of older S & W top-breaks were made, but I have never seen a copy of this model before.

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Alan
SWCA LM 2023, SWHF 220