Kalashnikov had the most bragging-rights with the higher-caliber standardized for it.
AR manufacturer's have pretty-much caught-up to the reliability-levels of any AK's in this current tactical market.
From 2011 onwards, Advanced Armament Corp (AAC) finally bridged the levels of caliber size, knockdown power, subsonic-suppressed shooting and middle-class affordability with the .300 Blackout