Glad you enjoyed the article, Jon.

With hold sensitivity, as with so many aspects of the springer shot cycle, we tend to hamper ourselves by seeking a single reason for any phenomenon, when there could be more than one cause, depending on a variety of factors, including how the rifle is set up, and how it is used. People find a simple relationship between recoil displacement and hold sensitivity appealing, because it’s easily understood, and we can alter recoil displacement at will. It is equally likely that the cause is recoil or surge acceleration, vibrations at some point in the recoil cycle, or a combination of these plus displacements. We just don’t yet know.

Jamie’s graphs are based on acceleration measurements. To find velocity, we have to integrate the acceleration data, averaging each pair of figures, which can mask large differences between adjacent figures, smoothing out vibrations. If you note the fluctuations in Jamie’s x axis accelerometer graph, you’ll see they’ve largely disappeared from the integrated velocity graph. Sorry, Jon, but when the pellet exits, the vibration is there, but you can’t see it because it’s been integrated out. The graphs in my article were direct measurements of velocities, and showed all vibration, but had I measured accelerations and integrated the data, the vibrations would be greatly diminished, if they showed at all.

We might know more about hold sensitivity next year. Nomads are hosting the inaugural UKAHFT 2019 Recoil HFT Championship on 26th May, and there will be plenty of rifles with short strokes, light pistons, reduced diameter cylinders and the like. I just need to convince the owners to let me test their rifles…