Yep, with you both on this one.

Just going by "simple logic" here, and no hard and fast scientific measurements. The "action time" will necessarily be longer with a longer stroke. Depending on the piston weight, recoil may be higher or lower (obviously lower with the lighter piston), but the duration of the forward stroke, and hence the first recoil phase, is longer. Springing it up more would speed things up but, if it's very, very efficient, the power may creep too high.

What we need is for Jim to get some of these on his rig, where he measures recoil, surge, vertical deflection of muzzle, pellet exit point in relation to where in the cycle that will be (generally in the early stages of surge). On the recoil and surge fronts, he records the deflection and duration.

Quick thought.....with a longer stroke, one would expect the measured rearwards recoil to be of a longer time duration (but maybe less deflection due to lighter piston), so "longer but softer", but do we think the piston bounce may also be longer (and softer)? If so, this is where the extra hold sensitivity has got to come in?