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Building An Accurate AR-15
The other key ingredient-the barrel-initially gave me night terrors as I tried to decide which one to use. Like optics, the more I learn about barrels the harder it is to settle on one. I can’t afford premium barrels for personal use, so I’m always stuck between budget and need. As luck would have it, while talking triggers with Mr. Geissele at SHOT ’08, the General Manager of Wilson Arms happened by the booth. After playing “20 Questions” with Mr. Steven Pawl, I decided to take a chance on a Wilson barrel for the project. My only reluctance was that their barrels are only available with button rifling which I suspected would hamper downrange performance. After SHOT I ordered a medium contour, button rifled, 1:9, chrome-moly, 16" tube with a threaded or “post ban” muzzle. I planned an objective evaluation so I ordered from a wholesaler, avoiding any hand-picking. I chose a non-chrome lined chamber and bore, since my wife has no intention of fighting in the jungle or shooting hundreds of rounds between cleanings. The barrel I received is of good quality for a lightweight carbine barrel, currently turning in consistent 3/4 MOA groups at 100 yds with factory fodder. I’ve built several rifles since this project using Wilson barrels, and found all-including chrome lined versions-to be in the same category. None of these are marketed as match barrels, so I’m very happy with that performance.

Building An Accurate AR-15
Some of the basic tools needed for AR assembly include (clockwise from L to R) a good torque wrench, barrel nut wrenches, non-marring hammers, punches and lower and upper receiver blocks. Photo courtesy of Rifleman Consulting LLC.

When I started this project, I was operating purely on theory. I was positive the gun would be safe to operate before presenting it to my wife, confident it would function and cautiously optimistic I could put the pieces in the right places well enough that my wife wouldn’t suspect I was clueless. But I had no idea how well or poorly it would shoot. In the Army I’d either used mass-produced rifles and carbines with their mediocre accuracy or precision long-guns tweaked by very talented sniper-rifle ‘smiths. So after the initial 10 round “Whew, it didn’t blow-up” shoot, I went to the first range test with a blank sheet of paper. The break-in process hinted that this carbine would shoot in the “acceptable” category. After break-in, and prior to other accurization steps, the carbine shot consistent 1 MOA groups with several different factory loads at 100 yards. While not astounding performance on paper, I was happy to see it grouping and happier to be able to tell my wife her rifle worked. Being short on patience and long on inquisitiveness, it wasn’t long before I began learning how to make ARs shoot better. Several carbines and heavy barreled match rifles later, I’ve learned this venerable platform is worthy of a second look for anyone dismissing it as inaccurate.

After learning some tricks and ensuring all my light carbines were shooting well (including tightening my wife’s project gun down to 3/4 MOA) I endeavored to build a heavy barrel rifle with an eye towards accuracy. I figured if the first one didn’t pan out I’d keep that little project to myself and stick with shorter range hunters and tactical guns. Since I already had luck with non-match barrels, I decided on a low cost gamble that wouldn’t dent the wallet if it turned out to be a dog. I opted for a 20", 0.936" (OD), button rifled, chromemoly barrel from Olympic Arms. As with all my barrels, this one had a 5.56 NATO chamber. I tried several factory “match” loads and had terrible performance, not surprisingly the worst were loaded for .223 Remington chambers. The best I could get were a few .9 to 1 MOA groups with Hornady 75 gr. AMAX factory ammo. On a hunch I tried the favorite load of all carbines I’ve built: Hornady 55 gr. V-MAX. I promptly hit mass-produced pay-dirt. This cartridge averages .51" in all [5 round] heavy barrel rifle groups I’ve shot, with the best to date being .261" at 100 yards. Overall, this mid-sized V-MAX has been a superbly accurate projectile in all of my .224 bores. The addition of adjustable buttstock, pistol grip and the much needed free-float handguard rounded out the heavy rifle nicely.

Tool Time
Not surprisingly, a few select tools greatly aid basic AR assembly. A bench-mounted vice is a must, coupled with an upper receiver block used to it firmly while all manner of services are performed. The next item is a lower receiver block, which locks into the magazine well, stabilizing the lower so you can install the trigger, receiver extension (buffer tube) and all small parts. It’s important to get the right size upper and lower receiver blocks for large (AR10) or small (AR15) platforms. Another AR-specific tool is a barrel nut wrench. I have several types and all have their pros and cons (hence owning several). The basic function is to remove or install a barrel nut but some combination versions also work on flash suppressors/muzzle brakes and free-float tube lock rings as well. A good torque wrench is helpful for certain parts of the gun. Just as with turn-bolt rifles, ARs benefit from proper torque on barrel nuts, muzzle brakes and optics mounts. I have several because I’m constantly switching barrels and parts but one good torque wrench would suffice for someone interested in building only a rifle or two. Lastly, a brass/polymer/rawhide hammer and good set of punches—roll pin, steel, brass and nylon—will make life easier. Having extra 1/16" punches will make life a lot easier. As I’ve gained more experience, I’ve bought or made additional specialized tools for different accoutrements and functions, but they’re generally unnecessary for someone building just one gun.

Assembling an AR isn’t particularly difficult, but an understanding of the parts and how they function is important. I suggest researching direct impingement gas operation in general, and AR function in specific before beginning such a project. AR triggers range from fairly complex to dirt simple, depending on type and brand. Again, if you lack basic AR-smiting skills a web resource like AR15.com is invaluable. The folks that have taken time to photograph and detail all assembly steps deserve a pat on the back. It’s important that applicable safety procedures are followed during and after AR assembly/accurization, just as with any firearm. If in doubt about things like barrel nut torque and bolt/barrel headspace measurements, let a professional do it for you.

Building An Accurate AR-15
The tool list for accuracy work can be extensive but the basics include a receiver lapping tool, lapping compound and receiver block as well as tools to clean up or repair a muzzle’s crown. Photo courtesy of Rifleman Consulting LLC.

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