My 25 Wildcat velocity varies from 780 to 820 fps with JSB MKII 33.95 gr pellets, this seems like too much to me as vertical stringing per Chairgun indicates this would result in a variation of 1.34" at 70 yds. The rifle has had about 1,500 pellets thru it and has been back to AOA for warranty work on regulator for velocity variation of up to 130 fps and magazine indexing problems. The barrel has been cleaned a number of times with no effect, pellets are unlubed. What is a "normal" velocity variation and what are the possible causes for high variation?