The rings (4 stamped double circles?) were to indicate the shotgun was proofed for modern ammo (likely 2 3/4" 12ga). There should be lots more markings and stamps that would further direct us to finding it's age, value, and whatever else.
These folks made fine shotguns, drillings (shotgun/rifle combos), and double rifles. I've seen pretty beaten and abused low end models go starting at $3500. I've also seen some quite nice ones with $11,000 price tags.
Rednecks... Keeping the woods critter-free since March 2, 1836. (TX Independence Day)
I'm going to use the words "clip" and "Long Colt" every chance I get. It grinds my gears to see new members attacked when we all know dang good and well what's being refered to.