Guest post by "Dilandu" Question: we have target standing behind the transparent glass.
Why "capable" mecrs couldn't just use optic-wavelenght laser to shot the captain dead from, like, 100000 km away? They have spaceship with some weird atmosphere-control field. The laser cannon is a child toy comparable to that.
Also, the "let's just shove the barrel outside" is a Very Bad Idea. Outside is vacuum, direct sunlight (a lot of direct sunlight), radiation... Basically, the different parts of the weapon is in completely differen environment. Most probable outcome - BOOM in hands of the sniper.