Jsb, aa, fx, superdome, superfield, would be a good place to start. Front on shots, like shooting between the eyes, it is a rumor pellets deflect off there forehead..how true I'm not sure. Stick some bottle tops out at diff ranges out to about 45yrds, see if you can hit 5/5.
I think jsb deliver the best whack in any gun iv owned, .177. An a mate's mk4 .177 using jsb whacks too f.p. good luck.
P.s pellet testing is a twat, but once you found it , you'll be well impressed with the tx