range report on rock island 38 super

[JB75]

After a problem feeding hollow points(solved with a new mag and light polish) I went to the range withsome assorted ammo(Aguila,magtech,Pmc,Cor-bon, and Glaser powerball). All fed well but the cor bon would not extract about every 3rd round. The power ball was great 60 rounds no problem like wise for the others that were all ball ammo. Should I chalk it up to a picky gun or is there something a miss (the power ball is the hotter round at 100 grains at 1525 fps compared to cor bon 115 grain at 1425 fps)