Hypothetical question. I've had a look around but not found an answer yet. So for HFT, recoilless springers are in the open class. We take this to be semi-recoiless rifles such as the TX200SR, or twin piston rifles such as a Diana Giss/Whiscombe etc What if a new springer was made, one which was designed from the ground up to have minimum recoil but did not use twin piston or a sledge. What if the recoil was so low it could barely be discerned, but some measurement, maybe an accelerometer, proved it recoiled by 0.1mm or some other low number. How is it determined what is recoiling and what isn't? Where is the cutoff? I'm not thinking about any current tunes or rifles, or trying to find a loophole that will give me some advantage (I'm quite happy with my TX). Just a thought I've been having.