On my brand new, as yet unfired other than the factory, LMT CQB MRP 16" I have noticed a "loose" sound when fondling...I mean handling it. I thought it was the empty metal 10 round mag rattling in the mag well. Today, since my wife and kids have all gone to the stables to ride, I got some YouTube video's going on AR takedown so I can familiarize myself with the basics at least. This is when I noticed the "rattle" or loose sound, is coming from the fit of the upper into the lower. It is specifically at the area of the rear take down pin. If I hold the lower firmly, either by the grip or the stock, I can move the upper side to side a goodly amount. I threw a vernier across it, holding the upper all the way Left and then all the way Right in relation to the lower....the vernier jaws between the outside of the forward assist and the frame of the weapon lower, right at the area of the barrel nut. Not perfect but it gives me an idea of the play. I got a difference of about .3mm. I converted this and the best I can tell is that this is about .011".......somewhere around 1/64" I think. I was raised on metric so my small inches increment knowledge is a bit strained. I can "see" 12 thousands though because that is what motorcycle points used to be adjusted at. About the thickness of a matchbook cover.......this is consistent with what I see in movement side to side. A tickle less.....011" makes total sense to me, going by what my eye sees. It is like a semi auto handgun with a loose fit of the slide to the rails. I gotta tell ya, I don't like that. I know I did not buy a match grade weapon, but that model is still a more expensive type offering and I would expect tolerances to be tighter. Not only that but surely that amount of slop will translate to a much greater amount out at 100yds or more? Won't the weapon slamming in and out of battery not have a tendency to return to a different spot each time? So, is this a normal amount of wiggle or does it seem like a lot? How much do your weapons move side to side at that point? I don't expect you to measure but is it noticeable.....can you make it rattle if you shake the gun? Maybe it is normal or something stupid I am overlooking being as I am new to the platform but I'd appreciate some feedback. BTW, you folks have been extremely helpful so far. Thanks.