OK, So I think I'm gonna take the plunge and buy a used Pre-Ban Benelli M1S90.  What do I need to check for?  I've handled one once, but I've never seen the internals, so I have no clue what I need to check.  Any help would be great.

btt

Tough question.

I have an M1s90, it's several years old and has seen occasional heavy use.  Probably a case of buck, a case or 2 of slug, several cases of shot.

Most of the time it sits against the wall near wherever I happen to be in the house.

It has never jammed under any circumstances.

I even used it and my rifle sights to shoot a round of clays a couple weeks ago.  Functions perfect despite internet claims that they can't cycle with bird loads.

All that said, the bore is hard chromed (I think) and the park is tough.

It looks new inside to me, so I guess look for one that looks new, cause if it looks beat, no telling how much it's been used.