Well I have knocked deer to the ground over a hundred yards with my 6 inch 629 Smith. I have not killed a lot of squirrels with pistols. If I had a buddy that we could have a friendly competition I would go more because I have more squirrels now than I remember. I have a older Ruger 6 & 7/8 inch barrel that is probably just as accurate and a 5.5 inch bull barrel Browning. I would say you could shoot them 25-35 yards on a regular basis. And if your eyes are sharp and hand steady ocassionally hit them out to 55 yards. These pistols are as accurate as you can aim and shoot. You can shoot Sweetgum balls and hickory nuts all day long if you do your part.
I used to and still mostly shoot free handed without a rest. But you could lean against a tree and if the squirrel is still and you can squeeze the trigger, you could easily take them under 40 yards. You need to practice some and learn how much front bead at different distances. Have it set to shoot even with top of rear site at 20 yards average. that would get you at say 15-25 or 30 yards. Then at 40 elevate the front sight slightly higher than top of rear sights. Up close, say 10 feet at a snakes head, you hold the front sight higher, even more than a 40 yard sight. Because the barrel is under the sight and is climbing so to speak. With practice at different distances, you can do it without thinking much. A 5.5 inch bull barrel or one of the Browning slab side barrels, they are highly accurate too. I like the trigger on Browning 22 pistols. They are short pull and crisp. If you shoot the Brownings or Ruger auto 22 pistols enough you would be confident enough to use them for self defense if the need ever arose. I did not start shooting handguns regularly till I was about 22 or 23 when I bought my first H& R 22 revolverI bought my first Browning pistol, a Buckmark when I was in my middle 30s. They are fun. I have a new in box Ruger bull barrel that I have owned several years that I am going to shoot one day that I bought for an investment.I have a S&W 22 auto , I love S&W revolvers and some semi autos but I have never taken to it like the Brownings or Ruger. But is accurate too.
I think they are about or close to the same accuracy wise. I like my Keltec PMR-30, 22 magnum.and how it carries. it has a light trigger. But I think it is a little on the light side for squirrel hunting and a little too much power. But I have been toting it to my hog trap
Mostly CCI , I have shot some Speer Short barrel 22 mag ammo. I have it strapped on now. I am fixing to go and check the hog trap.Let me clarify what I mean that the PMR-30 is a little light. I mean that it is light as a feather.in weight And while close shots are easy, it might be difficult to hold steady free handed for shots over 25-30 yards. I use hollow point ammo and it would probably be better to use solids on squirrels unless making head shot so as not to tear up too bad.