The ARMS 40L that I had rocked quite a bit and if sand got in the spring it wouldn't fully engage upright.
The PRI gas block version I saw was the worse, it would almost flop side to side.
I now use Troy flip up's and Daniel Defense fixed, these are not High Power Match sights, they are decent BUIS's. I can make A zone hits out to 300 yards. I never cared for the sight picture of the Magpuls but they were useable.
I like those DD fixed sights. A friend let me try them and he said that is what he used in Afghanistan. He says they are built right and he trusted his life on them. From the looks of them, I would agree. He has a red dot set up in QD's for that rifle. No problems there that I can see? At least for his use. He doesn't have an issue qualifying with the set up.
