old topic but... any updates?
as for testing, couldnt you just get 2 of the same gun, and rig one with a 7mm shaft and a single 20mm rubber and the other gun with a 7.5mm shaft and 2x16mm rubbers and shoot at a dense target, like rubber or plywood.
then just measure penetration of the shaft.
you could do different variables as well, such as gun length, shaft length, target distance. people could do tests with whatever guns they have and post results and someone could tabulate it all.
just a thought
as for testing, couldnt you just get 2 of the same gun, and rig one with a 7mm shaft and a single 20mm rubber and the other gun with a 7.5mm shaft and 2x16mm rubbers and shoot at a dense target, like rubber or plywood.
then just measure penetration of the shaft.
you could do different variables as well, such as gun length, shaft length, target distance. people could do tests with whatever guns they have and post results and someone could tabulate it all.
just a thought