Nice work DonP!
I do have some concerns with your use of putty as a target media though:
-varying thickness in putty target
-many putties are non Newtonian
It seems that your putty pad isn't very thick. Thin pads bring the backstop into play when the putty deforms and backs into the rigid backstop. I would think that a very thick pad of putty (say 2") would reduce the effect of varying thickness to the backstop by taking the backstop out of the deformation behavior altogether.
Most putties tend to be non Newtonian. Their apparent stiffness is highly deformation rate dependent. Faster deformations may absorb more energy than slower ones which directly affects the damage potential we wish to observe.
I think it is also important to also measure the muzzle velocity just before the pellet impact. Making an assumption of constant energy may be a mistake when you're trying to correlate performance with damage potential.
2m is not exactly point blank in airsoft terms. IRC my shots at my Prochrono indicated up to 20fps velocity loss with high energy rifles shooting 0.2g pellets at 10'. Heavier pellets exhibited lower velocity loss. I think you need to blast your targets at 6" instead of 2m (~7')
Want nearly free GBB gas?
Last edited by MadMax; November 5th, 2008 at 02:26..