The Sonic Pistol is a weapon used by the officers of Terra Nova. Like today's handguns, it fires lead bullets fed from a magazine which is loaded into its grip. When killing a target is not necessary, the pistol can, with the push of a button, switch to a non-lethal weapon similar to the sonic rifle; thrusting a target backwards with a focused blast of sonic energy.
It is used in "Proof" by Josh to break open the freezer to steal the drugs for Mira. This is the unconditional favor Mira asks him to do to get Kara on the Eleventh Pilgrimage. Boylan then uses it to shoot Willy, to cover for Josh and pay off his debt of 500 Terras.