Gear Scout wrote about Sig Sauer's MCX. This uses. 300BLK and with titanium suppressor, keeps the rifle report to 120db. While this is not ready for market, it is exciting. They are planning to add Keymod rail system, and some minor features.
http://blogs.militarytimes.com/gearscout/2014/04/17/on-the-range-with-sig-sauers-mcx-black-mamba/
From: Gear Scout
