That's a great find. Squeezing enough speed out of an Arduino to do airgun timing takes a little work. It will be interesting to dive in and see what he did. Might even be able to add a trip wire to the muzzle to get a timing mark for the pellet leaving the muzzle.
As for ending the springer hold debates.....I think it would provide some fresh data for the debate to chew on for a while.
Thanks for posting this.