just to give some constructive suggestions I feel that having this weapon where it shoots and goes under ground would give that player too much power.
1. being that it would be harder for the player being hit by the weapon would make it much harder. For him to find the other player before more damage was done
2. this weapon would also be good at hit and run but to me too much so. It would shoot and would take a little for the pay load to be delivered and so by the time it hits the other player. The player with the weapon would already be gone from that spot and relocated to another ready to fire on the enemy. The guy being hit tho would not know at first what was going on and start to follow the trail it left behind only to find no one it there.