A 9MM will probably be louder than a .22 (rimfire).
But still, abrahamsmith, there are plenty of reasons to shoot 115-147 gr 9MM bullets at "sub-sonic' velocities - besides being "quiet." Low velocity has its own advantages.
There is no reason to "push" any firearm platform to its "max," even though a cast 115-147 9MM at (say) 800-1100 fps) wouldn't do so.
The "standard" .38 special 148 gr HBWC Bullseye load at about 750+ fps will do so much that most of us have forgot it ... It really is one of those "do everything" loads. & really, (except for a heavy-duty "kill every thing else" load), why would anybody "require much else? (unless going for a "big-game, or "defense" loading.") - It is just not "required."
Before anybody starts off with a "labgrade's an idiot & can't play with The Big Boys," retort, I do have some fairly hefty handgun loads that do some things other than desired regards just a "nice light 9mm, or .38 special" loading. I can, & do "play" with "The Big Boys" reagards handguns.
Point is, & regards the initial post, a "workable" cast 9mm bullet at about 115-147 grains at about 700-~1200 fps would certainly do everyting asked of abrahamsmit's intitial post requirement - a nice, light load, that will do what he wants.
Far as accuracy goes, he may have to reload & work up to something that works in his own shooter. May entail bullet seat-out (for COAL), or maybe playing with the (variations of) powders ... & that's beyond what we're talking about here.
Want more? Goto Reloading forum, & I'd bet we could fix him up ....
"Worst case?" - I''ll load the damned things for him myself & give him a very decent medium range, small game/plinking load for him.
Frankly, this is one post in
handguns that actually didn't recommend going to "the biggest/heaviest/most powerful bullet/loadinfg" out there ... fairly refreshing, all-in-all.