This should be a product of Anciens Etablissments Pieper, Herstal, Belgium. If it has exposed hammers and damascus barrels, it's probably a little more than 90 years old; with hammers and steel barrels, around 1910 +/- would be pretty close. If it is hammerless, probably quite a bit newer and would be valued as a shooter. The only price guide I have that lists Pieper shotguns is 20 years old, but they are a bit lower than similar products from Crescent in it. Based on that comparison, I'd say current value for your Royal Gun Co would be in the neighborhood of $150 for any of the hammer-guns and maybe $200-$250 if it is the hammerless.