You want to use a repeat loop to spawn bullets.
For example if you had 2 bullets spawn, one on either side, in 5 degree increments, you would use
+ System: Repeat 16 times
-> System: Create object Bullet on layer 0 at (0, 0), create hierarchy: False
-> Bullet: Set angle to Bullet.Angle+LoopIndex×5 degrees
-> System: Create object Bullet on layer 0 at (0, 0), create hierarchy: False
-> Bullet: Set angle to Bullet.Angle-LoopIndex×5 degrees