About 30 years ago there was a guy here in Minnesota who bought an old house in St Anthony Falls which is actually part of Minneapolis. He was an electrician and was rewiring his house when he found a Thompson submachine gun with a drum magazine wedged in the rafters. He called the cops and they came and got it. It turned out that it was purchased back in the days before they were outlawed, and most likely hidden when they were outlawed.
People aren’t just born stupid, they make themselves that way with hard work. That Thompsons would be worth a mint, and the government has no business regulating something in your possession that is found in the house.
Were these weapons even serialized and better yet registered? If not, the least I would do is find someone with deep pockets and make a few grand selling it to a collector. Instead, some govt agent has nice trophy or a wad of cash.