I should have said, I made that project yesterday after reading your problem in order to try to provide a better solution for you, but then it turned out that things seemed to work alright without script.
It's very possible that using a 36-state sprite works better than using an 8-state sprite because an 8-state sprite has to accelerate in one of 8 directions while a 36-state sprite can accelerate in 36 directions, being much more precise. So you might want to try switching to see if that works better for you. Keep in mind that just because a sprite has 36 states doesn't mean in needs to have 36 different graphics. If your bullet sprite is large and complex, you could continue using 8 images and just split them into 36 states so that each image maps to 4 or 5 states. Or you could take it up to 12 images and have each image map to exactly 3 states.