I'm assuming you got the front bridge mount. Those work fine but you have to remove it to field strip the pistol....then re-zero. A $30 BSA red dot from Walmart works fine....but looks like a barrel of oil sitting on top of the pistol. The trick would be to find a small one. I think the small reflex red dots are what need to go on the P22. The problem with all of these is that I don't think you get any magnification. The size of the dot you choose should be determined by the type of shooting you intend to do. Target, small moa dot. Action shooting with quick acquisition of target important, then get the larger 4 moa size dot. Turning the brightness of the dot down when target shooting allows me to see the aim point better. Too bad there is no good way to mount one of these small red dots right to the slide. We've discussed ways to do it for over ten years. Red dots are really good sighting aids in my opinion. 1917
This is the correct size red dot for the P22 in my opinion. Not my pistol but back in one of the threads regarding how to mount one of these small reflex red dots. $50 to $400 models. This one was glued on by someone, there is no dovetail...he melted the red dot base to fit the shape of the slide and then glued the sight on. I think it worked for a few shots and then flew off. These are excellent sights but there is no way to mount one to the slide. One might be mounted to your bridge and probably would look a lot better than those big round ones.
Thanks for the comeback, 1917. Agree that photo #1 looks like a garbage can balanced on the bridge of the slide. I bought a Truglo unit at my range for $70, it more closely resembles your second picture. It has the screen and the sending unit about 2 inches behind it. It's a 5 MOA, red and green unit, interesting they don't come with any instructions. I'll attempt to sight it in this coming week.
I enjoy reading all your responses, they give me a lot of knowledge.
The big dot will be good for bright light. There should be windage and elevation screws somewhere on the sight. Don't forget to turn it off when you aren't using it....or you might have a dead battery next trip out. I have a Trijicon ACOG on an AR and it works well. The oddest thing about these red dots is that as long as you have the dot on the target that is where the round will hit if sighted in. Movement of you head doesn't matter.....just keep the dot on the X. Weird. The little sights are used on .45 1911s and all manner of firearms that really kick and they hold up fine.....if you can figure out how to mount one securely. Adjustments might be with a tiny Allen wrench. If you can't figure it out try UTube....there is a video on everything under the sun there. 1917