One of my 99s (22) is causing imense frustration, checking power with Ftts 11.3, with RS 10.3 but with hobby 11.9!. My other 99 also 22 gives relatively constant power at 11.3-11.6 with same pellets , similarly my Hw30 remains constant with same pellets 7.7-7.9 so any ideas as to why one 99 can give such very variable power? Have stripped a few times and nothing appears amiss - good seals, bumslide lubed, spring, guides top hat all look good. Both 99s have had tins of pellets through them and I have cleaned bore in case such was cause.