"That wont work on my gravity feed. It leaks paint past the needle seat if I do."
I'm not sure what you mean by needle seat, Paul. If you mean the front end of the airbrush, yes, it can leak if you pull the needle back too far. Like I wrote, it's touchy. If you mean the internal needle seal, the seal is leaking and needs to be adjusted or replaced. But, this would be a problem even in normal use.
At any rate, it's probably better to develop trigger control rather than to depend on tricks like this. And, that just takes some practice.