weapon swap help???

[ablizno]

ok so i made it so that there is a drive able sentinal by swaping the modle of the banshee with the sentinal......it shoots the sentinal projectile but not like the sentinal does .......... how do i make it so that the weapon shoots in a perfictly strait line.......like the warthog gun does....i cant swap warthog gun with banshee gun can i????