This patch will modify the direction the jeeps' bullets fire.
I've you've played SNES - Fire Power 2000, the bullets will work the same in Jackal, as in that game with this patch.

if your jeep is stationary (no D-Pad input) then the bullets will fire in the direction the jeep is facing.
If you press a D-Pad direction then fire, the bullets will fire in the direction you've pressed.
If you hold down the bullet fire button, the bullet direction will be locked until you release the bullet fire button

NOTE: there is a glitch where if you hold the bullet button before a level starts, the bullets go haywire.
A bug from the original game (if you press the grenade button on the first frame of a level, the grenade goes no where)