NAA Mini-Revolvers are Great Guns!
.22 magnum is effective. Yes they are loud, and the ammunition costs more than .22 long rifle.
My personal favorite is the .22 ling rifle with 1 1/8" barrel.
I do recommend sending in to NAA for the lanyard loop.
For ME the .22 long rifle is less expensive allowing more quality practice.
This ammo is available anywhere, and all one does is find the loads their particular shoots POA/ POI and use those for carry loads.
Now I often use CB longs when introducing new shooters with these guns, less noise, recoil and the focus in on safety and technique. These loads are effective for pests in the garden too.
Now I and others have used these worn around the neck and in deep concealment crotch holsters.
Another gun is a Beretta Jetfire, this one being .25ACP, What I and other miss not being on the market is the Beretta Minx, that fired .22 short.
Well made guns that deep conceal well, great triggers, accurate and reliable.
Tiny, deep concealment we hope we never get to the point we need to use these guns - I still believe in quality practice with these guns.