OK, I'm a little confused about all this ridiculousness. I've pinned my 10 round AR magazine, so we're strictly talking about a pinned magazine compliant build, with a straight up 16" threaded barrel. If I go featureless, then I can't have anything but a pinned (and welded) muzzle thread protector. So, let's talk muzzle devices/protectors when I DO pin my magazine. Do I ALWAYS have to pin my muzzle device choice at this point? If I want to have a pistol grip and adjustable stock (extends below the trigger), do I then have to pin my muzzle device, or can I not have one? If I add my Thordsen stock, do I STILL have to pin my muzzle device? If I pin my magazine, and my barrel is a straight up 16" in length, can I have a muzzle device that I can keep UNpinned? I mean, what's the formula in a nutshell? I have all the stuff to easily pin the muzzle device of my choice. I'm just not sure when I HAVE to do it. I mean, if I don't HAVE to do it, then I won't, but I have 4 AR builds, and I'm trying to get them all compliant, but I'm trying to avoid pinning anything I don't have to so that I can have multiple set ups, between the different upper and lowers I have. Thanks for reading!