Hi Jim, I found that the ptfe sleeve was the culprit. Without it, and running at 10.3ft/lbs it was much more consistent over the chrono. However, the ‘boing’ was back!! I thought a little more preload might help, so I added a washer to the bottom of the piston and one at the spring guide end too. Over the chrono, 7.9’s were just over 800 ft/sec. Remembering your lgu article in AGW, I swapped to 8.44 Exacts. 775 ft/sec; 11.25 ft/lbs. Now, for years I’ve preached 10 to 10.5 ft/lbs is the place to be with springers. However, my lgu likes to run above 11... made apparent when (and this is not boasting) I put 10 pelets through a 12mm hole at 30 yds!! Hold sensitivity is much better and no discernible increase in recoil. I think I’ll leave things as they are now! Thanks again those that gave input. Sorry this reply is sooooo long!! Jez.