GURPS High Tech is less than helpful with a few things. Flashlights get the barest of descriptions, listing only a range for the light beam, although I recall seeing that light beams were 1 yard wide somewhere. Thanks to Roll20, i'll be using a board that can only be seen by the players when things in darkness have the light beam on them. Since the whole game takes place in tunnels, I plan on using this a lot, so it helps to know how to approximate.
I'm also working on weapons for GURPS Metro still (nearly done, at least with the main post!), and building the general purpose liquid unpleasantries sprayers based on modified squirt guns from High Tech 180. Problem is that the squirt gun lists things like RoF 3.5/2 and Shots = Jet. I'm guessing that's supposed to mean that it gets 3.5 shots per pint (2 pint tank). Range is listed as special, but doesn't give much in the way of where to find it. I know I've seen it somewhere, but I'll have to hunt a bit as it isn't made obvious.