Building a National Match AR

How to build a National match AR

A year or two ago I decided to try some three-gunning. For those unfamiliar with three-gun competition, it is essentially a type of match where the competitor uses a rifle, pistol, and shotgun, in multiple and combined stages, and operates under time and scoring constraints, plus whatever the sick, sick planners of the stages decide to insert into the course.

It’s a lot of fun, and can be very challenging, however it also has a very high round count, as in hundreds and hundreds, and requires three guns, which can be pretty inexpensive, but can also be very not inexpensive. I decided that I wasn’t quite ready for that, but I still wanted to shoot ARs in some sort of competition setting.

The JP adjustable gas block has a set screw to allow the user to tune the gas system. Just make sure the Loctite is set before you shoot, or it will blow out around the screw like in this picture. Note also, where the author made the slight modifications to the handguard swivel attachment point, and to the bottom rear of the sight's rear clamp to allow the incompatible to become compatible.

The JP adjustable gas block has a set screw to allow the user to tune the gas system. Just make sure the Loctite is set before you shoot, or it will blow out around the screw like in this picture. Note also, where the author made the slight modifications to the handguard swivel attachment point, and to the bottom rear of the sight’s rear clamp to allow the incompatible to become compatible.

What I settled on was to shoot CMP sanctioned matches using the General Service Rifle rules. Now, I’m not going to go into the details of this type of match, simply for lack of room, but I will relay a couple of hints. To find the entire rule book, which is not insufferably long, it can be found in PDF version here.  In a nutshell, you need a 20-inch AR-15 with a carry handle. On the exterior it must remain orthodox in appearance, with the aforementioned 20-inch barrel, standard handguard, carry handle, standard military sights, standard pistol grip and stock, etc.

There are minor modifications to the exterior allowed, such as a non-threaded barrel with no muzzle attachment, a detachable carry handle, a stainless steel higher quality barrel, a free float tube that uses the standard handguard halves, several different minor but useful sight modifications (such as a corrective lens or finer adjustments), and the ability to use pretty much any color you want for the stocks if you want to be something of an individual. There are also a few must-have criteria that will be mentioned in italics as we progress.

Most large AR manufacturers such as Colt, Rock River Arms, and DPMS offer purpose-built models for this type of competition and generally they are quite good at it. However, I am loathe to simply buy a complete ready-to-use product, so I decided to go a little further and build my own from parts.

Fortunately, Brownells was able to offer most of what I needed. With all the insanity of the AR market with its super special aftermarket stocks, pistol grips, and doo-dads of whatever persuasion there is still the good old inexpensive A2 stock and pistol grip, which are required by the rules. These came from Brownells with no hassle, and included the receiver extension tube (buffer tube for you non-purists), buffer and spring. Truthfully, I can’t stand the A2 pistol grip, mostly because of the finger groove on the front of it. The little projection is entirely in the wrong place for my small hands, and ironically the grip itself feels too skinny, probably because I’m used to using MagPul pistol grips. Well that’s tough since my choices are A2 or A1 grips, and since the rest of the rifle is A2 configured, I reckoned that putting an A1 grip (without the finger rest) would just look stupid.

Also from Brownells was the NM free-float tube made by Rock River. Most shooters can sling up a rifle so tight on a front-sight-mounted sling that it affects the point of impact. And probably no shooter can sling up in a sufficiently repeatable fashion to affect that point of impact the same exact way twice. So the handguard, in addition to being free-floating, also has a sling swivel on the front/bottom of the inner tube, thus transplanting the sling-up stress to the tube rather than the barrel. This makes this tube much superior to the standard handguard for accuracy, but also makes it substantially heavier, since it’s made of steel. Most competitors don’t mind that weight since it helps to keep the entire rifle more stabilized.


Recommended Resources for Gunsmithing

 

Gunsmithing with Patrick SweeneyGunsmithing with Patrick Sweeney CD

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Gunsmithing the AR-15

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5 thoughts on “Building a National Match AR

  1. 762x39ar

    I’m in the process of not only building a 7.62x39r AR, I’m also building a lower for my brother (active duty Navy), so he gets as much practice from a reliable 5.56 NATO chambered weapon as possible before he returns Southwest Asia. I think the book would make some great reading material for him on deployment.

  2. Rifleman101

    This is a great build. I had this idea last year, but was told by the rules committee at the CMP that the JP Low Mass bolt and the JP Adjustable Gas Block front sight would not be legal for CMP competition. Please clarify.

    1. Kmura

      This may be the case. When this article was written, I had it on reasonable authority that these items would be legal, as the rules indicate, generally, that internal modifications and parts are acceptable (low mass carrier, trigger, etc.), and the gas block remains very close to original appearance. Furthermore the gas system still remains fully operational. However, perhaps something new has developed…

  3. biggrumpy1

    As stated elsewhere, I do not own a modern sporting rifle (aka AR-15) at this time. I think that the book “Gunsmithing the AR-15″ would be a great reference book for when I do own one (notice I said when not if).

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