Subjectively : -):
Untunned PGPs having classic "Ploop" sound, tunned PGPs after hammer lightening have sharper and shorter "Pop", hightly tunned long barreled scheridans have "Puf". With this PGP it has changed theo "Pop" to smother "Pluff". Sound signature is now somehere inbetween tunned longbarreled sheridan and tunned PGP without porting... closer to the PGP.
Along my experiences having groves alot better effect with decreasing of the pressure in the barrel, but they let the gas go out with far highter speed, so they do not limit the sound signature so good as larger nummer of small holes (when there is space for them).
I have avaited efficiency loss and from this reason I have used only small holes. But optimall will be combination - small holes in middle of the marker, below one side of pump handle and shorter groove on other side, near the muzzle. Perhaps ther last 3-4 holes should be conected in groove.
Great invention - thank you for inspiration!
Last edited by 3022; 03-28-2013 at 08:45 AM.