Dude, the shock rifle takes NO skills. Just fire a shock bullet, and shoot it down when it's close. There's NO way to avoid it in a cramped tunnel. The rocket launcher takes skills, because you actually have to aim, and calculate the ballistic speed, plus that the victim has a CHANCE to avoid the rockets.

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram