Selecting the "Clays Gun"
Bill doesn't have a hunter's soul, so he satisfies his love of shooting by breaking clay targets. A primary requirement for success is the ability to fire two shots rapidly. Shotguns which can do this are:
The double gun:
Any well-made (and therefore durable) over-under or side-by-side double may be used. The over/under is by far the most popular for clay target shooting, as it offers a cleaner "sight picture". You can't go far wrong with any gun made by Browning, Beretta, or Ruger. The Browning Citori is perhaps the best value for money, but a good used F.N. made Superposed is worth consideration.
Double barreled guns break open, and are very obviously safe when opened - no small consideration when you are shooting with a group of other people, as this feature is most reassuring to your fellow shooters. The simple handling, ease of cleaning, and polite nature of double guns make them favorites among clay target shooters. Their one drawback is that they do nothing to reduce recoil.
The self-loading gun:
Autoloaders are less expensive than over/unders, and do offer one other very significant advantage - a substantial reduction in felt recoil. Their mechanism simply distributes the recoil impulse to the shooter's shoulder over a longer period of time than a fixed-breech gun does. This is perceived as a less noxious sensation. As target shooters may fire 100 cartridges in 2 hours, this is a desirable trait indeed. Many top competition shooters select an "automatic" for this reason alone. The type does have drawbacks: it is less durable than a good break open gun (an auto will last perhaps 30,000 shots - a decent over/under well over 50,000) and safe handling requires more care. Autoloaders are also much more time consuming to clean. Competition shooters are willing to provide this extra effort in order to shoot higher scores! Remington autoloaders are reasonable guns, but the best are Italian, made by Benelli and Beretta.
The pump action, so robust and reliable in the hunting blind, simply cycles too slowly to produce competitive scores.
Those who shoot for pleasure and are not too bothered by recoil usually shoot a double barreled break-open gun, almost always an over/under design. Keen competitors and the recoil-shy will select a self loader and live with the inherent annoyances of the type.
An additional consideration:
Many currently produced shotguns have screw-in chokes. You'll appreciate these if you ever need to use steel shot. With lead, fixed chokes work just as well.