Hadn't thought of a combro, but it wouldn't be very pretty if it was in shot. I was thinking about trying to capture the pellet as it emerges from the barrel. Sound activation would be OK, and given the pellet comes out at approx 70% speed of sound and there's an inherrent (but small) delay on the flashes it should be about possible if you put the microphone a a few yards away from the muzzle.
ISP Airstream MK III No 15 which is a bit poorly at the moment and having a rest
AA Pro Sport + Ginb FT8 stock + Bushnell 4200 6-24x
EV2 MK1 + Leupold Comp 40x
Weihrauch HW100 KT laminate
SBFTC Competition Secretary