Make sure you introduce gunfire (noise) in high excitement situations. Start with the noise far away and gradually move it closer. And ALWAYS when she's ramped up and/or chasing something.

The noise (gunfire)!should ALWAYS be associated with positive experiences/fun.

Some dogs don't need this careful approach to gunfire but some do. It depends on a dogs individual temperament and prey drive.

You'll need to watch her and her reactions and advance as it's appropriate for the dog you're training.

Its much easier to introduce gunfire properly than try to fix a gun shy dog later.