Probably a model 85D or 185D. Sounds as if it may be missing a screw, or sear may be worn. These were utility grade shotguns- not fancy, but pretty durable and reliable. In GOOD condition- about $85. I have an 85D and a 183D (410) that I use as a loaner, let grandkids shoot, etc.
What we have here is... failure- to communicate.