The shop I go to (personal friends w/owners) swears that you should buy the appropriate can for the caliber. Truth be told is that I probably would not notice the 3-4db difference with my poor hearing and I'll probably get the bigger can anyways. I want a AAC762SD and an Osprey 45 so that I can use them on 7.62 and 5.56 as well as .45 and 9mm.
Nov 2, 2011 sent form 4, SS Sparrow. Arrived May 29, 2012.
Jan 30, 2012 sent form 1 for SBR. Arrived July 12, 2012
Jan 22, 2013 Sent form 4, 762-SDN-6. Arrived Sept 13, 2013