After some strange results with pellets going high and low when they shouldn't. I went through the usual cleaning barrel ,check pellets , Chrono showed down a little on output with a handful of high and low fps between some of the 40 shot string. Turned the output up slightly ,seemed quite settled over the chrono now. Zeroed yesterday and seemed to be shooting okay then tried the tissue paper test on the breech that someone suggested and it definitely has air escaping . Could this be the issue all along ? Any advice would be appreciated. Thanks Mark.