Palmetto 12 guage shotgun
I also have a similar shotgun. It was handed down from my Father. It is a single shot, break back, 12 gauge, 32 inch barrel with a full choke. A dime is a snug fit in the end of the barrel. It has 'Palmetto' stamped on one side. I believe the stamp on the other side says Patented in May 07.
I break it out once a year for Thanksgiving. One shot at a turkey shoot usually yields a turkey. When I approach a turkey shoot with this plain long barreled gun, I always ask the other gentlemen in attendance for they consent. They stand holding very expensive guns with 28 in. barrels and reluctantly welcome me. I return their sportsmen like conduct by taking only 1 turkey. I welcome any information on the shotgun.