+1 on what Technosavant said ...
No organized clays course - is going to let you load more than 2 shells at any one time !! So forget the 12 shell issue ....I don't know where you got that from??
Good clays guns ....
a. on a budget a good pump gun - $500 or so....
b. around $ 1,000 - $ 2,000 some good semi-autos ...Browning, Benelli, Beretta, etc ...have lots of options
c. $ 2,000 - $ 4,000 Browning and Beretta Over Unders..
My personal choice in a semi-auto would be the Benelli Super Sport in a 12ga with a 30" barrel / carbon fibre stock / Inertia system - with Comfort Tech recoil supression system. In my area its selling for around $ 1,875.
http://www.benelliusa.com/shotguns/benelli_supersport_and_sport_2.php
My personal choice in an O/U is a Browning Citori, XS Skeet model, 30" barrels with adj comb...list price is about $ 3,600 but its selling new for around $ 3,200.
http://www.browning.com/products/ca...tent=citori-xs-skeet-adjustable-comb-firearms
But in general - most any shotgun with a 28" or 30" barrel --- that will hold 2 shells -- is a good clays gun. Built in adjustability is a big plus / so the gun hits where you look. Don't get too hung up with what the mfg thinks is a "field" gun, vs a "sporting clays" or a "skeet" gun ....most any of them are fine. But these days you get what you pay for in terms of shotguns ...lots of issues on lower end guns ...but with companies like Browning, Beretta, Benelli - they all give you a lot of gun for the money! Have fun in your search.