I have a ACSS HUD 4-14X44 that I have fielded with my TOBR 18" while I am putting together the cash for a MK6. If I ever get the MK6 I'll put this on my precision 5.56 build. I really like the fit and finish and the glass seems pretty decent. The chevron tip is a bit dull and it looks better in the pics showing the reticle than in reality. Back in December I bought this scope from a guy on the EE. It was in good shape and everything appeared to be okay with all of the original paper and box. I put it into a LT104 and put it on top of my TOBR. The adjustments seem to be right on as I can dial 3.1 mills at 5800 elevation at 500 yards and beat up a 6"x6" plate until the problem occurs. I am getting a shift that is not really consistent. After shooting 10 rounds or so I sometimes begin to get a shift of about 1-2" at 100. The groups stay small (around .5-.75) but I am getting a shift. As I continue shooting and make adjustments I get a shift back near the original POA and have to make adjustments again. This is frustrating. I have already checked to make sure the barrel nut is tight as well as the rings and mount. I am also shooting FGMM 168 with the same lot number.
I contacted PA and told them about the problem and without a second thought they gave me an RMA number to send it back for them to look at it. I realize that they did not have to do that since I got it second hand, but I really appreciate it. I will give an update when I get it back. I also plan to take this set up to a LE NRA precision rifle school in August, and hopefully I can give a review on the performance.
Update: Primary Arms took care of me. I have a new scope on its way. I'll get some review up after taking it back to the range. Thank you Dimitri!