OK, I'm going to disagree with some of the above...
The 20 vs 12 gauge recoil debate is pretty much a toss-up:
http://www.chuckhawks.com/twenty_vs_twelve.htm
That being said, my brother-in-law, who owns several hundred thousand dollars of shotguns, CLAIMS that the same model 20 ga will kick more than a 12...
I own a 12ga side-by-side Zoli, and a 20ga over/under Browning Citori. I freakin' LOVE my Citori (http://www.ozarkguns.com/Browning/citori_superlight.htm). It's the one with the straight stock (no pistol grip). It's light - which is great for the field, and just a heck of a lot of fun to shoot. BUT, being light, it does have a bit of kick (part of the recoil equation includes the weight of the gun).
All that being said:
Skeet shooting, you will score better with a 12 ga. Just look at the scoreboards where you shoot - the 20ga shooters are a few percent less than the 12ga shooters.
12ga shells are much less expensive than 20ga. You can buy cheap loads at WallyWorld all day long. 20g will consistently cost you more. If you choose a 20ga, I'd suggest reloading.
12ga shells come in a MUCH larger selection.
Double vs. pump vs. Auto. If you have a pump or an auto, you still only get 2 shots when skeet/clay shooting. If you dove hunt, you are only allowed 3 shells anyway. Someone did a study on the 3rd shot when dove hunting a few years ago, and the hit rate was insanely low. Doubles are generally more reliable than pumps, and pumps more reliable than autos. OF THE SAME MAKE. There are lously pumps and lousy autos. Personally, I'd stear clear of used autos. If they weren't well maintained (and most aren't), it will never work well. My brother, who is an avid waterfowler (probably 30 or more days a year) swears by his Benellis. He has 3.
If you field hunt (like for quail), with a double, you don't have to worry about where your shells end up (they fly out of the pump and the auto) - with a double, you can track your bird, rather than your spent hulls AND your bird.
If you plan on doing some waterfowl hunting, make sure you choose a gun that will handle long magnums - many field guns won't.
Like most things, the gun is a personal choice. Pick a few up, handle a few, and buy the one that fits you best. And if you would like to borrow my O/U Citori, just let me know.
Last edited by Bill S; Wed, 4th Mar 2009 at 11:53 PM.
Bill
215g FOWLR... and anemones, GSP, gorgonians... carp, that isn't FO!
"I killed my first SW Fish in 1971..."