4.5 inches is the magic number to keep all ammo subsonic. I have a Ruger MKIII threaded at this length with 20K rounds through it and no problems. My favorite is CCI standard velocity. The good thing is you are not stuck shooting only subsonic ammo. Bulk pack stays subsonic and cheap to shoot. Waiting on a second .22 can now and my next host will be a MKIV.
I have a 4.5 in mk2 that won't stay subsonic with Bulk pack. But a had a 3.2in? Walther that was always subsonic no matter what ammo I used fwiw
Maybe your altitude in Wisconsin but in the deep south I have never had any round of any brand go supersonic.
Nobody has said it but the Beretta model 71 best of the best
i use the ruger 22/45 lite
love it....put a RMMR on it, part of a trigger kit (you dont need the whole kit-1 part does 90% of the improvement--dont spend $150 on the whole kit..if you research you find its like a $25-50 part to fix it), sparrow 22, and a ring thingy for pulling the slide back.....kids love it...awesome gun....shooting it today!....i use cheap 25 year old UMC .22lr...if you wanted you wouldnt need headphones....
with a short barrel im not sure your getting any extra noise reduction over standard ammo.....i use this ammo with a 22 rifle and sparrow and i get 0 noise reduction...but in a short barrel its perfect....if your ammo costs extra it may not give you extra benefit....
get the ruger....i had a walther p22 and sold it..i was not happy with how it felt or worked....
I have 3 Ruger Mks. I like them because they last.
I did have the new S&W M&P Compact 22. I liked it. Cheap, reliable, easy to clean and accurate.