I have 2 "black rifles" a Rock River and a Bushmaster...I bought the Bushmaster first and one thing after another was bad on it (I bought it new). After replacing the barrel (with a 1:8 Pac-Nor) and the upper and having trigger work done it finally shoots ok....just ok...even after 2 dozen different load variations
I recently bought a Rock River...love it, drops ragged 1 hole groups @ 200 with just about any 45-60g bullet I feed it. Other than a minor trigger adjustment, the rifle has been a dream come true and in the long run it was less $ than I invested in the Bushmaster...so if I had it to do over, I'd go Rock River fro the get go.
That being said I also have 2 Mini-14's that out-shoot the Bushmaster a half the price...LOL