Jsb 25.4’s RD shooting about 950fps, this is factory settings!, I have no programer, 18.1’s shooting @ 890fps, here’s my issue with the jsb18.1’s first tin (from an old lot) shot excellent... friend give me some of his from a different lot# and they wouldn’t shoot for crap?, initially thought dirty barrel, tried with and without Moderater no go? So started inspecting pellets from old lot vs. newer new lot rear inner skirt and thickness quite significantly different? Seen this before especially in jsb .177 13.4’s which I shoot the most of any pellet! So you tell me?