Hi, I noticed you were interested in putting a red dot on a .22 -- Well my only .22 is a miniature revolver that makes my cell phone look huge. However I have tried putting red dot sights on my glock and shotgun...
There are mainly 2 diff. classes of red dot sights. Garbage... Expensive... I started off with a garbage red dot sight on my 9mm glock. The sight was not mounted on the slide but the frame for minimal recoil/movement. Still it could not handle it. It turns out those "Call of Duty 4" looking red dot sights are all made of the same parts... just diff. brand names... STAY AWAY FROM THOSE! If you want a flat screen red dot... Trijicon and Doctor are here with lifetime warranties that they stand by.
However the tube shaped red dot makes it easier to find the red dot on the screen.
When I realized a red dot sight failed to hold zero on a 9mm I was already over it and wanted iron sights. I decided to buy a red dot for my shot gun (I shoot slugs only) -- so I read all the reviews on Midwayusa.com and Planetoptics.com and determined that the Millet was the only affordable red dot that can hold zero on a shotgun (reportedly) -- I bought it, installed it on my shotgun, and I can use it to shoot clay pigeons with SLUGS!
The scope I bought was the 30mm tube model.
I now believe that red dot sights come in 3 classes... garbage and expensive... but then there's also millet!
The only disadvantage on mine is the edge of the lens is warped so the red dot can appear to be on the lens when it's not supposed to. But that's ONLY the very edge of the lens which causes no problems for me since I use it with a buttstock. Remember tube shaped red-dots are designed to be used with rifles or long guns.
Keep in mind while millet sights are great...their scope rings suck ass. My original failed so I bought another pair only to find that it has the same damage done to it as mine. I assume a lot people are having problems and returning the product to midwayusa.com who is not carefully examining the package and reselling it.
If you want a tight connection you're going to need to grind the screws to modify them so they can be opened with a flat head screwdriver that you trust. The tool they send you is made of cheap soft metal that warps quite easily along with the screws.
This is a minor downfall if you already have a rotary tool at home and can modify it a couple seconds.
Oh one more thing mine was a diff. model:
the good thing is when you change the intensity of the red-dot you virtually change the MOA