I've had a bunch of older students with the same problem and almost all of them ended up with the same gun...a Beretta 87 Cheetah.
The gun is a traditional DA but has the option of being able to be carried cocked and locked. If your friend's arthritis is too bad for her to fire the first round DA then teach her to carry it with the manual safety on just like a 1911.
And yea it "just a .22" but my last three shooting as a LEO were all "just .22s" and everyone was DRT...DeadRightThere.
Bob
Didn't they make a .380 ACP version of that gun, also with a tip up barrel?
