re: Shooting skeet: what gun would be good?

if you are shooting skeet you should be using a 12 gauge O/U.

I'm not sure if the OP is asking about skeet, or about sporting clays (which a lot of folks south of I-10 also call "skeet."

20 gauge is plenty adequate for either skeet -- but 98.3% of skeet, trap and sporting clays shooters use 12 gauge guns.

A semi-auto will help reduce recoil (and despite the ads you see, a gas operated semi will do a better job of this than an inertia system). This isn't that important if you're only gonna shoot an occasional round of skeet. But if you shoot 4-6 boxes in a session, and shoot a few times per month, it'll make a difference.

I know plenty of serious shooters who prefer an O/U. But I also know more than a few who have undergone rotator cuff repairs after years of shooting those O/U's.

I know a couple of good shooters who use pump action shotguns. You need to be very quick with a pump to handle the four doubles stations on a skeet field (and the true pairs at sporting clays).

Just my $.02