yes I've used and seen various 6mm's take elk, and some of them were with 100 grain bullets. U do your part and it'll do it's just fine.
Side note, you may wanna change the topic starter to say something about "100 grain bullets" instead of "black AR" as you may get a few more people to answer the question about the bullet as they may see the "black AR" part have no experience with the rifle and move on past. Poing being the 100 grain bullet pertains to the question and the black ar part doesn't. Just trying to help you get more answers is all. I know that Alpine Creek has shot a fair number of elk with his 243 and 100 Nozlers.
We've used the 6/06 to take a few elk with 85's to 95's and no issues either.
Dober
