Magpul advertises them as "theory based". As others have posted: I can take it or leave it. I really like ease of the bolt hold open and drop while sitting at the bench. I actually pulled it off my AR and reshaped it to work on my 15-.22. If someone gave me another one I would put one back on the AR but, I'm fine either way. I've had zero problems with it installed on either. (adapting it to the 15 .22 took some tweeking but, works fine) The one thing I would recommend is to install an enhanced trigger guard. The B.A.D. lever takes up a bit of real estate in the trigger area.