Yes, this should fit the S&W M&P15-22.
For those who do not understand how a M4/Ar15/M16 select firearm works‐ this trigger group will not magically turn your firearm into a machine gun. This is just the fire control group that works with registered machines guns (Machine guns registered to the ATF before May of 1986) or LE select fire ar15 pattern rifles. If you install this trigger group into a standard ar15 that was/is currently semi-auto only, you can do so legally, and it will continue to function in semi auto only. The full auto portion of a M4/M16 with select fire capabilites would still be needed and also illegal to convert without the proper paper work as a SOT.
in summary to those shopping and browsing who do not know- this will not turn your regular home build, box store, Gucci 3 gun, safe queen, basement LARP, ar15 into a bullet hose.