I came across this answer, someone asking something similar:
Coy- Hopkins and Allen made inexpensive handguns under a variety of names (both their own, and "trade names" for various retailers) in Norwich, Conn. beginning about 1867. The XL series (numbers 1 through 8) were most common in the 1870s and 1880s. The model number was related to the caliber, but I could not find precise identification of the "No. 3" but suspect it was probably .32 or .38 rimfire. Good vest pocket guns or to keep by the bed for shooting burglars, wild animals or wild people. Certainly not expensive guns, but comparable the inexpensive guns many people buy for protection now. Little collector interest, but a wonderful family heirloom. I hope you can pass it on to your grandchildren.
Aug 1997 Questions And Answers
Kinda hard to find info on the no.3 it would appear. Best of luck to you....