My TX200hc mk3 .177 (Tony Leach 21mm piston) loves:

1st AA Express 4.52
2nd JSB Exact 4.53
3rd AA Field 4.52
4th AA Field 4.51
5th H&N Field Target Trophy 4.52

(Crosman Domed 7.9 gr, was ridiculously accurate at first could have been first choice but then purchased a new tin which brought surprisingly shocking results)