It's broken.
It's not worth it take an spas in this case, all of the checkpoints or atleast 3 of them are in closed places, close roads, where you can spam crouch while shooting timing those "ghost" shots. I've been testing it and it's annoying, you can actually shot like 10 bullets in 2.3 secs.
PD: the animation while crouching doesn't even finish and the shots already came out of the stubby.