Smith & Wesson M&P 15-22

General Information

The Smith & Wesson M&P 15-22 is an AR-style rifle chambered in .22 Long Rifle.

The 15-22 forum on is probably the best source of information.

The 15-22 forum on is also a good source of information.

    This thread (542600) has tons of great information about what mods you can make to the 15-22.

Parts & mods for the 15-22:

Parts diagrams & Exploded Parts Views:

    Smith & Wesson does not officially publish an exploded parts diagram for the M&P 15-22.

    Patent info from the Firearms blog:

    Some parts information:

Disassembly instructions (with pictures):

Parts & mods notes from forums:

Last Shot Bolt Hold-Open Issues

If the bolt OCCASIONALLY does not hold open after the last shot, user RedNeck_Jim says:
This is a not-uncommon problem. It comes from a combination of two things: a too-strong spring in the bolt latch and a too-weak spring in the 25-round magazine. The solution has been known for several years, now.
Drift out the pin holding the bolt latch paddle and cut 1.5 or 2 turns off the bolt latch spring, then reassemble. Problem solved forever.  Use a 3/32" punch.  Do not need to drive the bolt catch pin all the way out.
It also helps to put a single drop of CLP or other cleaner/lubricant on the bolt latch pivot point.
If you search, you will see many discussions regarding this. I did this on my first 15-22 & have never had that problem again.

Here is one of the past discussions but there are plenty more:Last shot hold open

User tacticool22 adds: Also be sure to not hold the mag. Or even touch it or rest it on the bench. That could lead to bolt hold open issues.