The crown & scepter suggests British origin as does the name Patrick. If it is really percussion (muzzle loading) and not a breech loader with side hammers, it would date from after the invention of the percussion ignition system about 1832 to the general acceptance of the "modern" self-contained cartridges in the 1860's. The silver escutchion was for the original owner to have his name or initials engraved and is usually one sign of a "better" gun. Does it also have extensive engraving on the receiver and/or fine checkering on the wood? I have no information in my files for a maker named Patrick and my on-line source for data on UK manufacturers (internetgunclub.com) appears to be down.