It will definitely be a two handed weapon. But to accelerate a 0.1 kilogram bullet to a kilometer per second, much faster than I would but it makes the math easy, would require 100,000 joules. Doesn't strike me as a terrible drain.
LeeRoy said
You mean the T-800 at this point.
So Boerd said
Exotic weapon idea: Polonium 210 gas grenade. Only 3 nanograms per kilogram is enough to kill half a test population.
but would anyone actually know how to calculate the force of a punch?