I remember reading that it’s terminal ballistics were “impressive” at CQB/self defense distances during testing but I haven’t heard much about it since then. 
had a unit that had it last year. we only shot it out to 100 meters. the bullet has what appears to be a blue moly coat on it. it hits steel swingers about as hard as a 7.62 x 51 whitch is very unscientific, but it appears to hit it alot harder then normal 5.56 . i was also informed you won’t see much of it anymore.:mad:
It was an interesting load, but not very versatile. 6.8 mm pretty much eclipsed it.
That’s unfortunate, I wasn’t really interested in it’s versatility but it sounded like it’d fill a niche role nicely.
The ATK 100s we tested at Benning were, for all intents and purposes long tracer jackets completely filled with lead – very long and heavy.
A bullet that long will probably need something like a 5 or 6 twist to stabilize – they shot like ass (non-doctrinal, non-technical term) out of our 7 and 8 twist rifle barrels.