yep, you can shoot anything you want through it as long as it is 3inches and under (can't be shooting 3.5inch turkey loads). if your shooting slugs, dont bother buying expensive sabot rounds. Just go with regular foster slugs and save the money for more of them. Also, don't try to aim down the barrel unless you want a busted mouth or eye, espeically if its your first time out!
I'd recommend taking the gun apart (you punch one pin out and unscrew the barrel and the entire gun falls apart nicely), cleaning everything, lubing it up, and then shooting it. You don't actually have to do this but there are only about 7-8 major parts to the gun so its very easy and fast to do and can't hurt. For me, a clean and lube gun works and feels much better/smoother then one packed with stock storage lube/grease. Look on youtube for moron proof how to videos which show how to strip it and reassemble.
If you do intend to shoot magnum 3inch rounds or full powered/max dram slugs, do yourself a favor and get a knoxx spec ops stock. (pistol grip only was ment mainly for breaching doors and shooting non-lethal ammo after climbing out of a police cruiser)