Yes, I said it.
I know there are 10 million discussions out there talking about this, but give it some thought. The Sawed-off has almost no range, while all the other guns do, including the Gnasher. It also has only one shot. You can easily stop some guy charging at you with this gun by shooting him with a Lancer, Hammerburst or just about any other gun in the game. Take a few steps back, and let 'er rip. Unless you get blown away by some other guy, you should have no problem taking any of these guys down.