Lee Lapin beat me to it, but you'll have to find a semi auto with no action spring (or recoil or return spring or whatever you want to call it) in its stock. The vast majority of semi autos have their action spring in the stock. And finding one that doesn't have the spring in the stock is hard enough, but you'd also have to find an affordable one that has aftermarket options, so you can find a pistol grip. Good luck. (Seriously)