Subsonic 5.56?

With the larger grain weight, it still produces about double the kinetic energy of a decent .22lr round. Even comparing a basic 5.56 55 gr. round to a 40 gr. .22lr, the 55 is roughly 140 lbs vs 100 for the .22. That's still a 40% jump just with that. But it really jumps with grain weight increase. With all that said, that's why the .300 blk came to be. Specifically, for a supressed, SBR.