Close but not quite - Leapers UTG Pro Model 4/15 Carbine Length Symmetrical Split Slim-Rail System

From all the U tube videos that I watched, this looked like it was going to fit like a hand in a glove. Not in my case. I have the M and P AR 15 PSX piston driven gun and I had to modify the upper channel quite a bit to allow the piston to move freely when the rail was installed. I'll be the first to admit I'm pretty cheap and the cost of this rail was too good to pass up. But knowing what I do now and how much time it took to modify this rail I would have tried the Midwest Industries M LOK Drop In rail. From the images I was able to find on an internet search, I could see that the upper channel where the piston rod is located has much more room. The images on the Optics Planet doesn't give a very good angle on the photo to see the spacing. I really liked the options on this rail to attach the picatinny segments where I wanted them, and to leave it clean where I wanted a slimmer feel to the grip. The MI M LOK also has that option and I've also seen rubber inserts at gun shows that fit into the circular openings to allow a better gripping surface. It always boils down to personal preference but I just wanted to put in some feedback as far as fitment goes on this rail. Hope this helps.