I purchased a S&W M&P 15-22 last year after handling all of the .22 LR military style rifles, reading reviews, and talking with owners.
I really liked the feel of the HK and the SIG. They feel just like their big brother centerfires, especially the SIG. They are just a bit lighter.

The S&W was often mentioned as the best of the AR-15 styled rimfires, and it really does have the feel. Some US police departments tried different ammunition and found Federal to shoot best. I talked with Smith & Wesson and they said the chamber is tight, like a .22 match rifle, so the smaller Federal fits better. In fact, the cheap, bulk box Federal shoots very well in it. Now, if they would just get some back into the stores here.

I sighted mine in with the factor iron sights ( plastic, but good ), and shot very small groups at 25 yards, then at 50 yards. I did not have much time ( too many other rifles to shoot and adjust that day ), so I installed a Hawke 4x32 Mildot and removed the rear receiver sight. This is a good scope for a little rifle like this ( or an AR-15). With it zeroed at 25 yards and on again at 75 yards, the first dot below the crosshair was on about 125 yards. Half-way in between the crosshair and lower dot was right on the money a 100 yards, so I had a little fun breaking small pieces of clay pigeon out there.

I will probably replace the rear sight with an inexpensive flip up type so I can leave it in place and put the scope on and off. I will just have to see how I use it. Right now, I think I am going to put one of these same Hawke 4x32 scopes on an AR-15 for compatibility. The scope is very sharp, and 4x plenty for coyotes and foxes out to 400 yards.

Before I settle all this, I will probably mount a 4-12x40 AO airgun scope on this M&P 15-22 to see just how well it shoots at 75 and 100 yards, and which ammunition is most accurate, then put the 4x32 on it and take it squirrel and feral pigeon hunting.