Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
I've found the problem...
The hose barb that the piston seals against is screwed "upside down" so I had to wrap the teflon tape in the other direction (forgot about that).
I made a test shot at 245psi on a 3cm wooden board (5" nail) and it went right through.
Nice could the aiming fail be coming from the fact that you weren't shooting from rest?
Try resting the launcher on a bench or something and try shooting a group of 5-10 shots, with the laser attached and always pointing at the same spot - see if it groups at random.
Well jack's idea is the best thing either way. If it's random groupings you need to probably find better ammo. If your groupings are tight then it's just a matter of adjusting your laser to compensate for it.
"Who ever said the pen was mightier than the sword, obviously, never encountered automatic weapons."
-General Douglass MacArthur