Originally Posted by
tiriaq
The IVI Mk. 8z Ranger issue ammunition is not the same as the earlier Mk. 8z ammunition. There is an interesting story why not, but that isn't relevant to the OP's question.
Ammunition intended for use in rifles was Mk. 7 or 7z, loaded with 174gr flat based bullet; the sights were calibrated for it. The boattailed Mk. 8 bullet gave significantly longer range, advantageous for machinegun use.
As far as quality goes, DI ammunition shot better than DA. In addition, DI was Boxer/NC, as opposed to Berdan/C.