Incorrect. Look at the video in my last post. They shoot subsonic .308 through a very nice can and it still meters 126dB. The full power .338LM only registers 127-128dB through a .338 can.
A 168gr .308 sub sonic has a power factor of 176. I wouldn't feel comfortable taking anything larger than a coyote with one. A bullet will most likely have poor terminal performance in a larger animal like a deer. I just wouldn't trust it.
Sub-sonic=no breaking of sound barrier=no sonic crack. Must be a poor can. Have faith in a quality bullet and shot placement will do wonders. works for me.