I wanted to say something about regpressure and hammerstrike in comparison to harmonics, and my litle experiance with it. I am not an experianced tuner, but I am a owner of both a fx crown in .22, and a wildcat mk2 in .177. The wildcat has a huma reg in. On both guns I have tried velocity ranges from 800, and up to about 900 fps. I mostly shoot at 25m, I have spent allot of time with the wildcat, where the goal is to get as close to hitting or touching the same hole on a magasine of 8 shot. What I noticed from first tuning at the "knee" was that even the extreme spread was very good, the accuracy was not quiet what I hoped for. As I adjusted regpressure up about 5 bars at a time, I covered the same velocity range as before, by turning the hammer spring screw, and also went up to the new plateu. I have btw drilled hole in my stock, so I can adjust without taking stock off.
But the point is: At first the gun did shoot best at about 820-830 fps, even I could go much higher. Also the extreme spread was not that bad, even I was much lower than the "knee" velocity. Somewhere inbetween the "good range" and the plateu, the ES actually was worse, and also the accuracy was worse. I also discovered when I took a dryfire shot, the crosshair in my 20 magnified scope hardly jumped at all. Found it interesting that the gun actually "recoil" with no pellet in it. So when I upped the regpressure 5 bar more, the same thing happended again, the gun jumped less when dryfire, but with hammer striking harder as before, and the gun shooting faster. But only within a limited range. when I went down to the previous 820 velocity range the ES, and accuracy was not as good as before. Also the crosshair seemed to move a lilte more than before when dryfire. So in the end I did not care for the plateu velocity, or tuning for the "knee" anymore, and simply went for the velocity range where basically the crosshair had lilte dryfire movement, and tested more or less around that. So as increased pressure, and adjusted for the least dryfire movement range, both accuracy and ES seemed to drop in place by itself . Now I have for the moment setteled on 115 bar, shooting 10 grain JSB at 870-880 fps. Think I will keep it there for the moment, as shot count is good, and accuracy is also close to the one hole in 8 shots I aimed for, on a none windy day.
But the point is: At first the gun did shoot best at about 820-830 fps, even I could go much higher. Also the extreme spread was not that bad, even I was much lower than the "knee" velocity. Somewhere inbetween the "good range" and the plateu, the ES actually was worse, and also the accuracy was worse. I also discovered when I took a dryfire shot, the crosshair in my 20 magnified scope hardly jumped at all. Found it interesting that the gun actually "recoil" with no pellet in it. So when I upped the regpressure 5 bar more, the same thing happended again, the gun jumped less when dryfire, but with hammer striking harder as before, and the gun shooting faster. But only within a limited range. when I went down to the previous 820 velocity range the ES, and accuracy was not as good as before. Also the crosshair seemed to move a lilte more than before when dryfire. So in the end I did not care for the plateu velocity, or tuning for the "knee" anymore, and simply went for the velocity range where basically the crosshair had lilte dryfire movement, and tested more or less around that. So as increased pressure, and adjusted for the least dryfire movement range, both accuracy and ES seemed to drop in place by itself . Now I have for the moment setteled on 115 bar, shooting 10 grain JSB at 870-880 fps. Think I will keep it there for the moment, as shot count is good, and accuracy is also close to the one hole in 8 shots I aimed for, on a none windy day.