I am really enjoying my M&P22. It has run pretty much flawlessly since day one, and will eat pretty much any kind of .22LR ammo I feed it without any problems.

However, I am having a minor issue. On the right side of the gun (ejection port side) there is a tiny, hollow pin on the frame directly above the trigger guard. This pin starts to back itself out after 150-200 rounds in a range session. In a typical range session I will run 150-200 rounds through the gun. At the end of the session the pin will have backed itself out maybe 1/16th to 1/8th of an inch. I have to tap it back in so it is flush with the frame.

First, what is the purpose of this pin? Second, has anyone else had this issue, and if so how did you correct it? Maybe a tiny drop of loc-tite would work?

Any help or insight would be appreciated.

mine does the same, I just knock it back in...

M&P 22 pin worked loose!

M&P 22 rollpin coming out

I found these two posts regarding what sounds like the same problem. I just went and looked at mine because I've put about 800 rounds through it. The pin is gone!

So uhhh.. How vital is that piece? I don't know how long it's been missing. The old threads mention just going to a hardware store to get another. I was shooting a bit off the last time I was at the range, can I blame it on the roll pin, or do I have to fess up to just shooting badly?

That roll pin holds the entire firing mechanism, including the barrel in place in the frame - so it's quite vital.

Call S&W and have them send you a new one.

Just to be sure we're talking about the same thing here.. (This is my first handgun). When you turn the take down lever to 6:00 to field strip, there is a small notch in the take down lever that lines up with a hole. I can see right through that hole as there is no pin or anything in it.

Is this the roll pin location?

Edit: looking at this explanation of taking out the firing mechanism (http://www.ryanjay.com/mp22.pdf) I took a flashlight and shined it in the hole, and I can see what looks like a coiled up piece of metal or spring. I removed the slide and tried to move the barrel, but it is very secure. False alarm, I just didn't know what a roll pin looked like.

Yep. The pin that is supposed to be in that hole is just like the one at the back of the frame. It is a hollow pin with a split.

If S&W sent me a new roll pin, how difficult would it be to install? I am not very mechanically inclined, so should I take it to a gunsmith to have it installed, or is it something I could do without any special tools or ability? If possible I would like to avoid having to send the gun back to S&W and be without it for several weeks.

Trivial - just push out the old pin and insert the new. You will need a 1/8" roll pin punch and a small hammer. You may be able to use the new pin to push put the old.

I,ve had the same " trouble" since my gun was new. Now has 4000 + rounds. I do the same shooting 150-200 per range trip. When the role pin begins to back out, nearly every range trip, I tap it back in. It's not loose enough to fall out on its own, so I don't yet worry about it.
Yes, it's very important. It is one of two that hold the entire firing mechanism in place.
Check youtube for 'complete disassembly of S&W M&P 22. or S&W M&P trigger replacement.

UPDATE: Today I called S&W Customer Service and described the problem. At first, the guy I spoke with didn't seem to think it was much of a problem, saying that the pin wouldn't come out further than the 1/8" I described. I insisted that it shouldn't come out at all, and requested he send me a new roll pin. He agreed to send me one which I will try to install myself. While I had him on the phone I also requested a pinky extension for the second magazine that came with my M&P 9C, in view of the fact that it is almost impossible to find mags on the open market. He said he would check to see if they had any, and if they did he would send me one. Will see what happens..