While, ballistically speaking, a .300 BLK typically outperforms the circa 1940s Soviet-developed round, the obvious ability for SOCOM personnel working in areas where 7.62x39 ammo is widely available to utilize the round could be advantageous.
Among the details are a 7.75-inch barrel and an overall length of the upper of just 16.4 inches, as well as full compatibility:
SOCOM may be in luck as SIG recently debuted their first 7.62x39-chambered offerings in the MCX Spear-LT series. One of the options in that series is a factory SBR with an 11-inch barrel and an overall length of 29.75 inches, something that puts the company within striking distance of the RFI notice.
Either way, we'll keep you posted.
Banner image: SIG Rattler variant seen at the 2019 Army Expeditionary Warrior Experiments at Fort Benning (Photo: U.S. Army)