As I suspect many of us, I am intrigued at the idea of shooting a 30 cal bullet out of an AR.
I do have a few questions, however, that somebody hopefully can answer:

I do realize that a 300 BLK is not a 308, but what is the feasability of using it as a medium range cartridge (say 500yds)?

What kind of accuracy can be expected in this application?
I can tipically hold 1/3 MOA a 100 yds with my 308, sometimes out to 300 yds.

Using a medium weight bullet, say around 150gr, what kind of velocity can be expected from a 20" barrel?

Does a 20" barrel in this caliber even exist?

Yes, I know it is a round supposed to be for CQB, but it would be nice to be able to convert my 20" .556 and have a lightweight med range precision weapon...

Any imput?