Sunday GunDay: 7.5-lb AR for CMP’s Modern Military Matches

Retro is back — at least in the CMP’s Standard Modern Military Rifle AR class. Though Service Rifle competition has evolved to allow optics and heavy barrel profiles, the Standard Modern Military Rifle (AR category) is truly a “blast from the past”. Overall weight is limited to 7.5 pounds, and the rifle must be equipped with iron sights (Rule 5.2.3). In addition, the rifle “be based on the M-16 rifle or be based on an AR design” with “exterior configuration similar [to] the original military or military-type rifle”. See Rules.

With this in mind our friend Dennis Santiago recently put together his own AR-platform Standard Modern Military Rifle for matches run under CMP Competition Rules. This is not quite a classic AR, as it has a metal free-float handguard (vs. plastic handguards), but it IS light (7.3 pounds), and it does have iron sights — a key requirement for Standard Modern Military class rifles.

Here is Santiago’s CMP Modern Military Rifle (Standard Class) with an ultralight free float tube that has a titanium barrel nut, and mechanical, center-able front sight. The barrel is an AR-Stoner brand 20″-long 1:7″ Government contour chambered in 5.56×45 NATO. Dennis says: “This makes the 7.5-lb weight limit with a few ounces to spare. We’ll see how well it drives soon enough.”

Dennis explains: “The Standard Modern Military (AR) is a category of military-style rifle that shoots the 200-yard, 30- or 50-shot courses alongside the M1 Garands, Springfields, Vintage, and M1 Carbines. This one boasts a Midwest Industries (MI) ultralight Free-float Handguard and a Yankee Hill folding front sight. Any Government contour or thinner profile rifle-length gas tube barrel with a 0.750″ gas block will work.” Colt makes a suitable Government Contour 20″-long, 1:7″-twist barrel, sold by MidwayUSA.

To test the accuracy of his rifle, Dennis fitted a Mantis-X unit on the top of the float tube. The Mantis-X records the movement of the rifle to interpolate shot placements. Dennis reports: “I spent some extra time at the range grabbing a decent zero for my Modern Military rifle. I stuck a Mantis-X on it to record a few shots shooting offhand at the plates at 200 yards. It drives very easily even with no shooting coat or glove.” The Mantis-X is attached just forward of the carry handle, on top of the MI free-float handguard. The Mantis-X works with live fire as well as dry fire. It communicates via BlueTooth to a smartphone App.

Rifle Shoots Well with 77gr Sierra MatchKings
The gun is presently zeroed with 77gr Sierra MatchKing ammunition. Dennis reports his rifle “can easily hold the X-Ring on an SR target for both 100-yard and 200-yard CMP Modern Military Games matches. And it’s fun to shoot!”

CMP Standard Modern Military Rifle (AR Class)
This rifle is built from carefully selected and fitted parts to conform to the CMP’s 7.5-pound weight limit iron-sighted rifle rule. Officially, this is a CMP Standard Modern Military Rifle, Class “A” (AR type).

1. S&W M&P lower receiver
2. White Oak Armament match upper receiver with 1/4×1/4-MOA pinned rear sights
3. AR-Stoner 20″ 1:7″-twist 5.56x45mm NATO Government contour barrel from MidwayUSA*
4. MidWest Industries ultralight free-float handguard with a Titanium barrel nut
5. Yankee Hill Machine folding front sight with a 0.072″ square front pin
6. RRA 2-stage trigger
7. A2 length buttstock

Easy Rifle Build Using Mostly Existing AR Parts, Plus New Barrel and Free-Float Handguard
Dennis was able to put his Modern Military AR together using components he had collected over the years: “Most of these parts were already in my bin of old AR parts available to be recycled. The barrel and free-float handguard were the only new acquisitions.” And with the AR’s modular format, this was an easy build: “Assembly time was about 30 minutes. I’ve done these parts swaps so many times now.”

Key Rules for Standard Modern Military Rifle (AR Type)

Dennis Santiago’s new AR rifle was built as a “Standard U.S. Modern Military Rifle”, Class A (AR Type), as specified in the CMP Competition Rules.

5.2.3 Standard U.S. Modern Military Rifles, Class A
Category A Standard Modern Military Rifles must comply with these requirements:

a) Rifles must be based on the M-16 rifle or be based on an AR design;
b) Rifles must be manufactured by a USA manufacturer;
c) Rifles must be equipped with issue-type metallic front and rear sights; rear sights with adjustments finer than one minute of angle are permitted;
d) Total rifle weight, with sights and without sling, may not exceed 7.5 pounds;
e) Rifles may be fitted with a float tube or free-floating handguard. A nonadjustable sling swivel may be attached to the forward end of the handguard; and…
f) The rifle must be chambered for the 5.56x45mm or .223 Remington cartridge.

Also, from Rule 5.2.2:
a) The exterior configuration of the rifle must be the similar to that of the
original military or military-type rifle;
b) The trigger pull may not be less than 4.5 lbs.;

Comments from other Modern Military Rifle Shooters:

“I built a Modern Military [Standard]. It was tough getting below the 7.5-lb [limit]. I had to carve off a bunch of the 20″ barrel diameter but wanted to stay with it for sight radius (over a 16″). I would just as soon shoot that little iron-sighted rifle at 200 yards as my 15-lb Nightforce-scoped Service Rifle. I love that little rifle.” — Kenneth S.

“I’m building one of these that will make 7.5-lb [Standard Modern Military] weight limit, with the long barrel and long sight radius. This has been on my list this winter.” — Tom K.

“We found that turning down a National Match barrel and taking a few inches off of it made a very accurate rifle.” — Jack A.

“My old (complete) A2 upper has been sitting forlorn on a shelf for a couple of years now. Perhaps I need to do a [Standard Modern Military] build of my own.” — Derek D.

Dennis Santiago replied: “Derek — that’s the reason I was attracted to this. I had bought a brand new WOA A2 pin upper receiver to make a new upper then the scope rule was adopted and it was all flat tops. This gives new purpose to the old parts.”

CMP Rules Defining Modern Military Rifles

Standard vs. Unlimited, Class A vs. Class B

There are actually two different classes of Standard Modern Military Rifles, Class A for AR-type rifles and Class B for other military-style rifles, such as the M1A and FN-FAL. Ok, got that? Now, in addition, there is also a second division for UNLIMITED Modern Military Rifles, again with two classes (Class A — AR-type and Class B — other military rifles). These unlimited rifles can have optics, heavier weights, modern-design adjustable-length stocks, and other upgrades. Here is Rule 5.2.2 from the current CMP Games Rifle and Pistol Competition Rules:

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