Actually, one day at the range a couple of guys and I got a little bored with the "clang clang clang" of the metal disk, so we tried shooting horizontally.
There were no sights, of course, so it was hard to figure out hwere to "aim" at the 25 yard target... HOWEVER, it did seem easier to control the recoil this way, probably since the muscles of the arm seemed more naturally positioned.
After a little practice, one of the guys could hit the plate (12" across) every time quite easily.
I don't, however, expect it to be picked up by IPSC any time soon
