GreenO
I have had issues also with the 19S or #19ACOG Loosening some what with extensive use. Taking it on and Off especially when using your own site on a military Rifle, It tends to get loose. On the good side I have not noticed a shift in Zero, as mainly any movement is front to back and the zero doesnt change enough to notice. BUT Knowing that puts doubt in my mind and I dont shoot as Confident.
I have switched to the ARMS #10 It is a Duel Thumb Screw mount with spring tension on the locking Bar so It goes on and off very easily. In addition It has a deep groove the TA01 or similar site sits actually down in similar to if you mount one in a carry handle. This protects the site from latteral breakage of the mounting screws, if the rifle or site hits the ground or other object on the site. I saw one guy break off Both Screws on an NSN when diving from cover a couple years ago on a traning mission at the WET site In Western KY. Anyway this mount in MY opinion is the strongest and best one made for the ACOGs , Maybe not as fast, but FAST ENOUGH!!!!
chuck