My 177 hw30s has changed it´s prefered pellets from the first shots until now, i was having a big struggle finding the right on, at one point i was on my way sending it back cause it was so inacurate, first it liked the H/N FTT, then they where all over the place, changed to JSB 8.44 and they worked ok for some 100 shots then the same, back to H/N and they worked ok, but now i shoot the JSB 7.33 and they are more accurate than the others ever where, so i think it´s the gun that has been settling down and now is as it should be