glad I could help!
I assume you want the bullets to just fly in a straight line, for that I wouldn't suggest using a physics object as they need alot of calculation from the hardware.
Instead you could use the "bullet behavior" and set "angle of motion" to the direction you are shooting or to the mouse position if you are using the mouse to aim.
here a little sample how to use mouse position:
set "bullet" angle of motion = angle(player.x,player.y,mouse.x,mouse.y)