I once had a hankering to not only build an AR from parts, (as in the upper as well as the lower), but also to have an extremely accurate, low recoiling 5.56 gun just for fun, intermediate range plinking, (500-700).
While I was still in the Army, a buddy stumbled upon some 173rd Commemorative Edition stripped lowers, and I had my excuse to build one. What followed was an interesting adventure. I’ll lay out the parts used, as well as performance.
The key to an accurate precision gun is the barrel, (match grade, free floated), the optic, (quality glass in a good mount), and the trigger. By combining this trifecta in a well assembled platform, you can easily end up with a sub MOA gun, with minimal money invested. This isn’t a duty gun, (if it was, it would look much different), so keep that in mind. I don’t recommend building guns for serious purposes unless you have professional training, or are building it with the assistance of a person with said training. There’s a lot that can be messed up, with the loss of your life due to failure being the ultimate cost in a defensive shooting.
For the barrel, I went with a White Oak Armament Varmint barrel. It features their proprietary “Wylde” style chamber, (essentially an inbetween allowing accurate firing of both .223 and 5.56). It’s an 18 inch heavy barrel with no muzzle device, and a 1-7 right hand twist. I chose the 18 inch length because thats about where the maximum velocity of the 5.56 round occurs, without adding unecessary length. You can run a shorter barrel to good effect, however, if you choose to go that route.
White Oak is huge in the high power/service rifle world, and the prices are solid for the amount of performance you are getting. Additionally, the barrel included a rifle length gas tube and gas block, which saved me a bit of money.
The barrel was used in conjunction with a BCM stripped upper. BCM quality is extremely high, and the stripped upper included the forward assist and dust cover parts, as well as a slightly tight barrel extension diameter, which they say aids in essentially keeping the gun tight and accurate, (albeit in more technical terms than I used).
In order to freefloat the barrel, I utilized a BCM KMR 15 inch rail. This was an issue because I misread the inner and outer diameter specs of both the gas block and the rail, resulting in not being able to mount the thing. To get around this, I simply took a hack saw to the rail, cutting it short of where the gas block is.
Ghetto, but functional.
The lower was the previously mentioned commemorative lower from Sherwood Armory. I used a PSA lower parts kit, with a Geissele SSA-E trigger.
For the optic, I utilized the sweet military discount that Vortex provides, and paired their 4-16 Viper with an Aero light weight mount. My model is the MOA/MOA version, as I have no actual training on using mil reticles.
For the stock, I wanted something decent and adjustable, while not spending a couple hundred on the Magpul offering, so I opted for a Luth AR stock.
In the future, I might swap this out for either a VLTOR A5 setup, or alternatively a simple A1 fixed stock. The Luth stock is nice, but it feels a bit…. squeaky… which while not a tangible complaint, still irks me during use.
For the pistol grip, I went with a Magpul MOE, as it’s what I like, and it’s cheap. Pistol grips are always very personal choices. In addition to changing the stock, I’ll likely also eventually put a bipod and sling on the gun, as well as potentially getting it coated or just painting it, as having one black gun among it’s rattle canned companions hurts my brain.
I primarily use 20 round PMAGs due to their low profile. Performance wise, while using standard factory 55 grain ammo, (not match stuff), I can hold 1 MOA groups at 100 yards with little effort. I estimate that with some good match grade stuff, I could easily hold sub-MOA, but my skill would determine whether or not that was possible. Mechanically I think it would be a safe bet.
Overall it’s a very fun gun that I enjoy taking out. The recoil impulse is non-existent, and plinking steel at 500-600 yards with no effort is extremely satisfying.