OK, so I was using journalistic license, somewhat. I don't shoot on wide open ranges. In thick woods, that sucker is damn loud! My .480 is Magna-ported, and it doesn't come close. I shoot several .44 mag, a couple of .45 Colts, and a 50 caLiber muzzle loader with a 14' barrel, and with ear muffs, none bother me. With my Rowland, the muzzle blast seemed to almost hurt, even with muffs.
I would not bet on it not being enough to cause a rockslide, under the right conditions, though!
Mike
