The Carl Gustav 8.4cm recoilless rifle now be procured by the Marines has a big back-blast through the typical venturi used by these kinds of weapons. In training, (Sweden at least) they are limited to the number of rounds they can fire. I do not know if this for merely hearing loss, or if there are concussive effects.
Also, while "small arms" do not typically have concussive effects, I have stood behind a.50 Barrett rifle discharge and there was a noticable shock wave in the air. I didn't feel it in my head, but my intestines were not happy. If you were in the front hemisphere of the muzzle blast it would be far worse.
Muzzle brakes on rifles usually make the blast wave propagate more to the side. A high caliber rifle with a muzzle brake could easily hit 160db. Maybe a .50 cal could go higher. So now you are even punishing your friends, not just folks downrange.