I recently purchased an Ithaca 37 that has "US Property" stamped on the receiver. It is in the trench gun configuration. The story goes that the guy who owned it was a military collector and said it was an 80s prototype military shotgun. It is completely parkarized. The serial number is 3713690XX. It also has a three letter designation stamped into the side of it "LSP". Not sure if anyone knows anything about this but sure would like to know more about it. I've included a few photos. This gun has never been fired.