And those 62 gr bullets were going a lot faster out of m16's, than any 5.7-launched bullets...
But I do wish folks would quit saying the 5.7 is a challenge to reload, 'cause they're getting me intrigued, and I had really planned to go buy other stuff
If I did buy one, though it would probably be an AR57 upper for an AR15
They were also being used at much longer distances, so no, they weren't going a lot faster.
Furthermore, they were purportedly failing to tumble/fragment, whereas 5.7x28mm bullets
do not fail to expand/tumble/fragment (per any gelatin test or any shooting). In short, that comparison is useless.
