For loop unexpected behavior

Hi all

I have the following loop running for manual fire in my game

if mouse_check_button_pressed(mb_left){
    instance_create_layer(x,y,"Instances",obj_bullet)   

    if (powerup == 1){
        for(var i=0; i<=spread_level; i+=1){
            var _bullet =        instance_create_layer(x,y,"Instances",obj_bullet)  ;
            _bullet.direction += (spread_level*10);
            _bullet.image_angle = _bullet.direction
            var _bullet = instance_create_layer(x,y,"Instances",obj_bullet);
            _bullet.direction -= (spread_level*10);
            _bullet.image_angle = _bullet.direction
        }
    }   
}

​

I'm expecting it to make a new bullet on either side of the main bullet for each point in "spread_level"

spread_level 1 = 3 bullets

spread_level 2 = 5 bullets

spread_level 3 = 7 bullets

​

that's not what's happening though.

spread_level = 1 is resulting in 3 total bullets

1 aligning to the image_angle of the player sprite

2 others at +10 and -10 degrees

​

spread_level = 2 just makes the 2 additional bullets increase their angle by 10 degrees for a total of 20

spread_level = 3 - 2 additional bullets are at 30 degrees now

​

Any suggestions?

Thanks