The slide, barrel were completely in parts (even the sights hadn't been fitted). It is a plain black matte finished slide, phosphate I suppose. It is a completely bare style of round topped slide with the old fashioned fine grooves running perpindicular to the base of the frame, unlike the modern sloped/angled ones. This is good as I prefer the old style look.

The only marking on the slide (or anywhere else for that matter) is an M in front of the rear sight dovetail. I don't think it is a W.

A few years ago Thompson sold a lot of frame and slide assembly kits. It may be one of those.

Yeah, I know, I should have taken photos.