I am curious to know how the firer of the right-angled gun will deal with recoil and changing aim. The old Wehrmacht experiment with the curved barrel weapon (designed for street fighting in Russia, IIRC) proved unsuccessful. Of course, its descendant looks somewhat less impractical.
Others have made points about the practicality of laser weapons. There was a Horizon (BBC science documentary) on this subject back in the eighties in which I saw an experimental weapon mounted in a hemispherical cupola atop a modified LVTP7. Never seen anything like it since. The problems faced by energy weapon designers back in the eighties haven't changed much. The power requirements are the main handicap but there are others. Early experiments with high-power beam lasers fired at armour plate resulted in the heated plating vapourising and being drawn through the vacuum created along the beam itself, to the lens, which would be rendered useless as a result. Even then, melting a hole in something isn't necessarily going to render it ineffective. Pulse lasers, on the other hand, caused rapid heating and cooling in the target, and could result in shattering or exploding metal.
I don't have the links any more but D20 Modern players might also be interested in 'non-lethal' weapons research. Sticky air and ultra-low frequency sound generators coming to a region of civil unrest near you!
Lawks a'lordy, maybe that's why I play D&D.