So I finally got a chance to install my Ava mount on my M4. It went on fine, and as others have mentioned the mount itself is finished off very nicely and looks great. I am using a Surefire P2X Fury Tactical light (600 lumens). I inserted the light into the mount before tightening down the screws all the way, and discovered that when I rotated the light slightly, the mount captured the tail cap of the light, so there was no forward/rear movement, even before the final tightening of the screws. I don't think this was mentioned any where, but is a plus, because there is no way the light can move under the recoil of the gun. Additionally, there is enough space between the barrel/mag and the front of the light, to be able to unscrew it for battery changes etc. I am wondering if the body of the light will stay screwed into the tail cap under recoil? As others have also mentioned, the barrel and mag do create a shadow when the light is on, but this in no way impedes the overall functionality of the light. I am very happy with this setup. Here are some pics. Note my brand spanking new titanium mag tube from Kip and Marcy at Carrier Comp, which I also just installed. The only other mod is a Mesa Urbino stock w/riser & Limbsaver.