Rimfire is its own animal.
Have you ever shot your 45And your 300BLK can side by side? I'm betting , if you measured them on a decibel meter , they would be pretty much the same volume. My 300 black and my Glock 9mm are about the same volume. It's one of the reasons I only suppressed one or two of my center fire pistols.
"Quiet" is very subjective. We expect a rifle to be loud. And so the rifle can seems really quiet. We expect every pistol can to shoot like 22 rimfire and so when it doesn't , we think it's pretty loud. It's kind of like the people who think nine millimeter is really snappy in a PCC. Highly subjective.
Everybody has their own personal experience and\nSubjective evaluation of how loud "quiet" is. So I can't really make any universal statements about that. I'm just trying to suggest to the OP not to be disappointed. There may well be nothing wrong at all with his setup