If you're shooting 100's of practice rounds per week, sounds like you're looking for a gun for more than just sxs shoots. In which case I'd agree with Stan that a BSS with 30" barrels would be a good choice if you don't want to spend a lot of money--although the 30" 12's can be hard to find.

Another possibility in the same price range would be an Ithaca SKB Model 100 Magnum. They aren't all that common either, but they came with 30" barrels and a factory recoil pad, chambered 3" rather than 2 3/4" which was standard on all the rest of the 12ga Ithaca SKB's.

And if you want to spend more--but not as much as a new RBL Sporting--you could look around for a Parker Reproduction Sporting Clays. Not a lot of them around. Came with factory choke tubes.