We abondoned using our trackers for live fire. This problem is only that much worse when used with a blowback system. Instead we created a 3D printed mount for the controller. Not as pretty but works much better.
As for hooking up the gun, we chose to 3D print a fake scope and used it to hide a Audrino MKR1000 that tracked the trigger press and sent it via WIFI. But we also had to have a solution that works both with controllers/trackers and mocap so it worked best for us. PM me if you want details on the circuit/etc.