barrels can be 'pellet fussy' which means certain brands, shapes, or head sizes will give better results.
unfortunately each barrel is unique and what works for one might not work for others
there are some general good quality pellets out there such as JSB, AA Field, Daystate, H&N, Falcon, RWS
and there are some crap ones out there too.
the shapes of the pellet claim to give it certain properties that would be desirable such as extra penetration with pointed pellets or extra range or whatever... its mainly just a gimmick by the manufacturers
Just stick to a good quality