reduced mass movement I would suggest!
But this is not about accuracy or grouping size, it's about having a perfectly good group suddenly shift to another position and produce a perfectly good group there!
Pellets leave the barrel at a particular speed, they drop at 1g, at 55yds a pellet will drop a set distance for it's given launch velocity, for the pellet to drop less it will have to either get there quicker, or be aimed higher, so unless your pellet is changing it's BC considerably during the firing cycle and arriving downrange much faster it's not going to hit higher.
If your muzzle velocity is constant or within reasonable parameters then there is no way it can fly an inch or more higher at a given distance, which is why I am sceptical this is anything but a change in hold.
Last edited by Artfull-Bodger; 25th June 2015 at 02:59 PM.