I have all but 2 M70 calibers with BOSS! At the range BOSS or no BOSS I use DOUBLE ear protection! I only hunted with 243, 270 and 30.06 BOSS, since 1997! The way the angle of the ports is cut, it effects people around you more that the shooter! Facts!
A 308 with a brake (my 20" AR10) is louder than a 300 WBY without a brake! Fact! I hunted with a 300WBY without a brake for 10 years and no protection during the hunt!
I never handed with my 300 win msg boss or my 338 win msg boss!
I only state things I have experience! If it is an opinion, I say so! Just check my posts!