You will be the death of me Lello, could not resist a go even though I do not have a sound trigger.
I dug out the air pistol and clamped it in my milling machine vice.
Pellet stop is a plastic bucket with 3 layers of 200mm rockwool roof insulation. Tests showed the pellet only just made it through one layer.
Without a sound trigger I thought to short out and so trigger the flash using kitchen foil. Two strips, one connected to each side of the old fashioned flash extension terminal.
NOTE IF YOU TRY THIS ........ depending on the trigger voltage of your flash you can get a bit of a shock if you close the contact with your fingers by accident. I did so I know.
I chose to use my old Vivitar 283 for this experiment. Trigger voltage is quite high but I could turn it down to give a flash duration of 1/30,000 sec.
First shot was to determine the distance the pellet would travel once it had triggered the flash. Triggering is by the pellet force closing the circuit between the two bits of foil.
As can be seen there is not much delay so I will have to work on that one for a pellet exiting the muzzle shot. Also 1/30,000 is not enough to freeze a pellet so it could be a case of exploding food shots.
Second shot was just to see that I could do it. First grape hit dead on but failed to trigger. Workbench and background suitably splattered. Second shot and time getting on so I made sure the flash would fire even though the foil would be visible in the end result. Bench even more of a mess now.
Exposure info : Camera on remote 2 secs at f16, ISO200, Flash duration 1/30,000 sec. - workshop lights off but enough daylight for me to see what I was doing.
Don