SureFire has Flashhider made for .50 M2.
http://soldiersystems.net/2018/05/24/sofi-18-surefire-sf3p/
Glock Sub Compact Weapon Concept - Glock has some mix of commercially available parts thrown in to make this concept weapon.
http://soldiersystems.net/2018/05/29/sofic-18-possible-glock-sub-compact-weapon-concept/
