2 Solutions: Either use the same sprite and put all bullets in different frames of the default animation or Put all 5 sprites in a Family called BULLETS for example
For family method:
On [SHOOT BUTTON] pressed | Gun Create BULLETS >>> This randomly creates one bullet from the family.
For same sprite method:
On [SHOOT BUTTON] pressed | Gun Create BULLET <<< Sprite
On BULLET created | Stop Animation.
|Set frame to int(random(0,4))