The shotgun I learned on was a J.C. Higgins model 20 (IIRC), made by High Standard as the model 200 (IIRC).
Super slick action, reliable except for maybe some extractor issues. We had trouble with ours after many rounds, and I've heard of others with the same problem. I'm sure that is easily correctable though.
I have one now, that I picked up at an estate sale. Haven't fired it yet, but I'm looking forward to it.
Hold the gun barrel up and depress the slide release. The slide should drop of its own weight, that is a slick action!