Good morning folks, and welcome to Counterfett's Sci-Rifle top twenty! I was thinking of calling it Scifle, but that sounds too much like Psyfle- as in psyfleman, which is way too much of a heavy weapon connotation. First; some ground rules. These are the ones that I came up with, including all of the suggestions that I was given to boot. I am basing this on what I think is, 'more awesome.' There is no real qualitative way to determine which of a set of fictional items is better at a given task, since, again, they are fiction. If you don't agree with my countdown, make your own. Heck, let me know and I'll link to it!
Anyway, on with #20!
#20: Imperial Guard Lasgun
The Imperial Guard Lasgun, while often derided as a weapon shaped night-light, is in fact one of the most important developments in personal weaponry in its fictional universe. Light, safe, and effective personal laser weaponry that is easy to maintain, and cheap to load. As to effectiveness, since said laser has even a chance of killing a Space Marine in terminator armor, I would say they are very effective indeed.
Best deployed in large numbers, which is why they give them to the IMperial Guard.