People unclear of the concept -
Coroner Jacques Ramsay said in his report that the weapon used by Gill, a short-barrelled Beretta CX4 Storm rifle, should be banned. Gill obtained the gun legally before his rampage.
The Beretta CX4 fires 9mm, .40, or .45ACP. By banning that one rifle, you assure yourself that no other platform can fire those cartridges!!! Well, maybe the Kel-Tech Sub 2000. Oh, and that one by Hi-Point. Shoot, I forgot about the MechTechs. Dammit, I just remembered you can chamber an AR in 9mm.
Maybe banning one model won't have the effect required then. Back to the drawing board, then...