Originally Posted by rich
That can only come from a higher pressure at some time in the firing cycle, especially as so much less air is being used.
Thanks for helping me thinking about this Rich. But when you say it can ONLY come form a higher pressure I have to disagree.
It may also be that the peak pressure in a springer is lower but the average pressure over the first inch is higher. And this longer push may cause more acceleration tha a short peak push frorm a PCP. I think a spring piston rifle has a relativley (say 1 or 2 inch) longer push while a pcp has shorter peak push.
Also when a PCP would deform the skirt more this could increase the friction of the pellet against the barrel wall and result in lower efficiency of a PCP. See this picture: http://www.photosbykev.com/wordpress...s/_mg_9948.jpg
It shows a pellet shot from a PCP (daystate) at 85 fps (left) and the right hand pellet was at 780 fps. the 780 fps pellet has much larger engraving marks because the skirt has been blown out. So it wil have more friction in the barrel.