AERO PRECISION M5 LOWER in Building a .308AR Posted August 17, 2019 · Report reply 1 hour ago, Matt.Cross said: I'm just outlining the shoe size, whether or not you wear it is your choice. It is well known to most of us here that "AR-10" is common use phraseology, it's also well-known to be erroneous and irritating. My point all along has been that if you are going to indulge the erroneous and irritating behavior, don't expect it to be well received. There's actually a broader impact than just the annoyance of using the wrong nomenclature. Folks who are taken in by the erroneous use of the phrase suffer the inconveniences of purchasing incompatible parts for their "AR-10" because unscrupulous vendors don't care about the nomenclature. After a decade or so of helping those folks out, we don't have a real sunshiney outlook on the defense of it's improper use. If you aren't prone to using the term incorrectly, that shoe doesn't fit you and you aren't compelled to wear it. Now that you've been informed on the issue, it's up to you whether or not the label applies. Do you want to be part of the solution, or part of the problem? " People who call Aero's M5 platform "AR-10s", I call those people "idiots". You determined my shoe size for me because that's exactly what I did in this thread. I've been called a lot worse than "idiot" so take a number. I even posted a link in this thread that shows in PICTURES the Difference between Armalite and DPMS Large Frame AR Platform Upper Receivers. I'll leave this Forum in the hands of all the PERFECT People who never use generic terms in any of their language. Say hello to all the AR Police for me.