Just noticed that despite getting screenshots of the lasers changing direction, and of my troubles aiming down cliffs, I forgot to include them in my first comment. Have screenshots of both of those, and of a laser shot being blocked by a wall to the right.First off, aiming just slightly downwards (and I mean slightly) makes it bounce... strangely. For some reason, it stops going forward, and bounces... north? I think? It's quite consistent, no matter which way you face, if the angle it hits the floor is close enough to parallel it will bounce in that one particular direction. If this happens, it also seems to get stuck to the floor, so it starts following the slopes downward and whatnot.
The walls, meanwhile, like sucking up the laser beams. Going up against a wall and aiming even somewhat parallel to the wall tends to suck up the shot. If the wall is even somewhat onscreen, you can be sure your shot's being eaten.
Trying to aim down a cliff is also a bit hit-or-miss. You have to move so far forwards to prevent the shots from bouncing upwards, and combined with the recoil moving you backwards it becomes easier to just jump off before firing... before EVERY shot.