On another note, I have a related suggestion that doesn't deserve its own thread.
[...] So my suggestion is for all the projectiles to be in flight at once (not for all of them to exit the weapon at once because then it would look like a shotgun), and have the sudden stop only occur on the last impact.
this has actually been discussed before... the main problem is that while your proposed mechanics do make sense, they actually alter the gameplay.
one example: in vanilla xcom, if an enemy is killed by the first or second shot, it drops to the ground, and the following shot(s) can hit whatever (or whoever) is behind the killed enemy.
if all bullets would fly simultaneously, they would probably all hit the enemy before it drops dead.
so yeah, it would make more sense, but it would also deviate from the original gameplay. so right now, it's probably way down on any kind of feature list, since the official goal of openxcom is to make the game as vanilla-xcom as possible (at least in terms of gameplay - the controls are already way better...).