Actually, smite, there's a way around that. Every time it happens I just put myself near the edge of the screen and fire into the wall (or off the edge). The bullets should be back to normal, and if you turn around it stays normal about 70% of the time. If it continues to limit your bullets, just turn around and try again.
If I hadn't figured that out, the third phase of Clown Copter would've taken a lot longer than it did.