I hunted with the FMJ last year and they performed very well. My finished arrow weight was 575 grains, so they were some tanks. I have found the same thing with the breaking. It seems that they are either fine, or broken. I did bend one, but out of the dozen I have, four of them broke from impact with the ground/rocks/etc. I think I would shoot them again if I were going for some tough game that required more KE since they pack the extra weight and the super small diameter really penetrates. I have no experience with ACCs.