I originally had an NCStar D4B on the 15-22 since the reticle replicates the EOTech 512 that I have on my LMT M4. I found a great deal on a used 512 on another forum and mounted it when it arrived. Wouldn't you know it, right as the 512 arrived, I found another deal on an EOTEch XPS-2. It arrived today so I mounted it on the 15-22 for the heck of it. While I do really like it, it's still going on the LMT. I posted a couple of pictures just so you can see the difference in length in the battery compartments.
A couple of random thoughts. The 512 is well suited for the 15-22 due to the unlimited eye relief in combination with the long top rail on the Smith. The XPS2 is shorter, which tends to be better for some of the AR platforms. The 512 also adds a tad more weight which helps (a tad) in beefing up the 15-22 and getting it a tad closer in weight to its bigger LMT brother. Provided FYI.
A couple of random thoughts. The 512 is well suited for the 15-22 due to the unlimited eye relief in combination with the long top rail on the Smith. The XPS2 is shorter, which tends to be better for some of the AR platforms. The 512 also adds a tad more weight which helps (a tad) in beefing up the 15-22 and getting it a tad closer in weight to its bigger LMT brother. Provided FYI.