Building an M1 with the CMP

A few times a year, the CMP holds an M1 armorer class. At the end of the class, you go home with an M1 that you assembled and that’s pretty much guaranteed to work. Assembling an M1 has a little more gunsmithing involved than the shake-the-box assembly of an AR series rifle or the “make it approximate and it’ll work” construction of an AK. There are special skills — like lapping bolt lugs — and special tools required. Here’s the end product:

Freshly Minted CMP Special M1

Fortunately, CMP has the tools, jigs, fixtures, and most of all, the tribal knowledge to not only help you get your M1 right, but also to understand it and how that clever little Acadian intended for it to work in the first place.

Unfortunately, the annual quota is opened once the dates are set, and fills up in minutes. So it seems to be an insidery thing, to which we, and probably you, are all outsidery.

Fortunately (again! It always comes back around to fortunately) for all of us, blogger Keads (whom we don’t know, but think we might like), was one of the lucky attendees, and spent some of his time not just building a sweet Service Special Grade M1, but also documenting the process in three informative and photo-rich blog posts.

  • Part One: Begins with a tour of the plant and its facilities — including pallets of ungraded, yet, M1 rifles, vast metric craptons of ammo, and , of all things, an ultra-high-tech air gun range used by Olympic hopefuls. Then it gets M1-active, with the mating of barrel to receiver and reaming the barrel to proper headspace. One of the first specialty tools, a receiver wrench, shows up here (in a reverse of AR practice, the M1’s barrel is secured in a vise, and the wrench is used on the receiver). The bolt lugs need to be lapped for proper mating with the receiver’s locking lugs. Go to Part 1.
  • Part Two: With the receiver barreled and the barrel reamed to proper headspace, it’s time to start assembling the parts that turn a barreled receiver into an M1 Rifle action. The CMP armorers assist as the students raid the parts bins for inspected and refinished parts. The op rod has a special gage for both dimension and trueness, or correct “bend.” The trigger mechanism was, to Keads, the hardest thing to assemble. The class did both early and late M1 rear sights. Finally the fully assembled M1 barreled action goes into a new walnut stock — more hand-fitting is called for.    Go to Part 2.
  • Part Three: In the conclusion of the piece, the students hit the CMP store (MOAR GUNZ!) and final-prep the rifle (in Keads’s case, redoing the trigger) for test fire. You can take your rifle home or ship it (which makes a difference to which tax, if any, you pay). Here’s a snip of what Keads had to say, in retrospect, about the whole experience:

My thanks to the Armorers John, Ryan, and Chris. My thanks as well to the person that herds the cats around the Custom Shop and made sure our paperwork was in order and all the other ancillary tasks that made sure the class went well, Deshay. …. If you desire to own one and learn more about it, I cannot say enough about this class or the CMP. They have both the passion and the knowledge of these tools and it shows. It is one thing to be a subject matter expert and another to relay that knowledge to others.

Go to Part 3.

For those that can’t attend the class, at least you can buy one of the CMP rifles.  If you do wither of those two things, of course, you may need this link afterward. Just helping ya out.


Hat tip for this story, the incomparable Tam.

19 thoughts on “Building an M1 with the CMP

  1. Tam

    Keads is indeed good people, even if the revolvers he likes have cylinders that turn backwards. ;)

  2. DJ

    Great write-up and links!

    I should mention that my military M16/M16A1 armorer training included learning the use of aluminum vise jaw blocks to clamp the M16/M16A1 barrels, when any tightening, loosening, or torquing of the barrel nut was needed. It’s only in the last decade or two that upper (and lower) receiver clamping fixtures have become commonly used (and mis-used; I’ve seen a couple uppers and lowers damaged beyond repair by excessive or unopposed clamping forces); before that, it was barrel clamping all the way.

    1. Hognose Post author

      Interesting. I have seen bubba’d AR uppers and lowers a lot, but mostly it was from untrained Bubbas who clamped a receiver directly in vise jaws without any protection OR reinforcement. I’ve seen an upper twisted about 15º counterclockwise along its length from some genius torquing a barrel with a breaker bar or something. And in Army days, I saw a lot of uppers with what appeared to be vise jaw or pipe wrench marks (cosmetic damage only, really).

      ETA: really doubt any of that damage was done by school-trained armorers.

  3. GBS

    Good stuff. My experience with CMP products is excellent. My armorer rebuilt CMP “Special”, now five years old, performs flawlessly. Of the thousand-plus Greek Army M2 surplus rounds purchased and fired, I’ve found only one that I didn’t want to use (it was bent), and not one feed / firing / eject malfunction…ever.

    I was at the rifle range a couple of weeks ago, and had just finished with the M1. A couple of older guys who had been shooting bolt-actions and ARs walked by, looked at it, and asked “what is that”? Fortunately, my sunglasses helped hide my astonishment, and I was able to suppress the first words that came to mind.

      1. Y.

        Actually just 3kj range.

        A 40 MJ pulse rifle, that’d be launching a 20 kg projectile at 1000 m/s.

        That’s only going to be feasible for human use once someone figures out how to interface a brain-in-a-can with a robotic body. A really big one.

    1. DJ

      “What is that”?


      I suppose I wouldn’t be too surprised to hear that from a couple of 20-somethings, but for anyone who thinks they are a true gun enthusiast and is over the age of 40, there should have been SOME familiarity.

      I hope part of your answer included Gen. Patton’s phrase “The greatest battle implement ever devised.”

  4. blehtastic

    M1 Garands are the ultimate rifle. So sexy. There’s nothing more Americana.

  5. keads

    Sir, you could have at least told me you were linking to my Blog. Yes, h/t to Tam, but I have met her IRL. Finding out you posted this from a commenter on my Blog is bad form in my humble opinion. I have never been here before this. It’s no big deal and I appreciate it, but I’m admittedly old school in the new age.

    Take care and thank you for your service.


    1. Hognose Post author

      Sorry about that. Usually the act of linking leaves a trail so folks know I did it, but ISTR you’re on Blogspot and WordPress doesn’t talk to blogspot right, I think. I’ll bear in mind and leave you a heads-up if and when I link you again, so that you can know at the front end.

      Thanks again for your posts. If anybody else blogged a CMP maintenance/M1 class I haven’t seen it.

      PS — ETA — never any need to thank me for my service, I was having a blast! (Sometimes literally). As a kid and an incipient weapons man, my Uncle Jim told me, “If you want to play with guns, the Army has all the guns in the world.” Good advice if you get in to the right job.

      1. keads

        Thanks! I really was not expecting such a kind response. Get to NC sometime I’ll buy ya a drink! Thanks again for the synopsis of my posts. Nice to meet you out here on the Interwebz!

        1. Hognose Post author

          Damn! They should have linked YOUR posts because YOU were the guy who actually (1) attended the class and (2) wrote it up!

          Incidentally, I’ll be in NC in mid-July for the SOD reunion in Fayetteville. Dunno where you are in Tarheelia.

          1. keads

            Ah, no problem on the CMP link. You in fact wrote it up better than I! I am not that far away from Fayetteville. I owe ya a drink if I can get away from work or if it’s over a weekend, no problem. Well, unless it is the weekend I teach gun skool.

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