OKay fellows, this time I need some help. I picked up a double barrel percussion shotgun and can't find my book with proof marks. The gun is a typical 1870's period productrion gun in +/- 16 ga with a walnut stock, broken through the wrist and repaired with a nice copper wrap. All engraved hardware with damascus barrels and back action locks marked 'Belling" over "Bodmin". After dismounting the barrels I found a proof mark that is what appears to be a crown over crossed halbreds ove a triangle as well as double J's. Not one I am familiar with. Other than the usual rusty bores, trashed nipples and one missing hammer screw it is in pretty good condition. BTW the fellow I got it from has had it for 62 years and didn't know that BOTH barrels are loaded. Any help with the origin of the proof mark or lockmaker's name will be appreciated.
Mark