In your Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts upon an AR can actually affect accuracy – such as free-floating handguards, barrels, bolts, bolt carriers?” He wanted a genuine, well-informed answer, not only sales pitches. Robert Whitley posted an extremely comprehensive response to this inquiry, based upon his experience building and testing many AR 15 upper receiver for sale. Robert runs AR-X Enterprises, which produces match-grade uppers for top Power competitors, tactical shooters, and varminters.
There are tons of things that can be done with an AR to boost consistent accuracy, and i also make use of the words “consistent accuracy” because consistency is an integral part of it (i.e. a good amount of guns will offer several great 5-shot groups, but won’t do a good 10- or 20-shot groups, and a few guns will shoot great a day rather than so excellent on others).
Listed here are 14 key things we believe are important to accuracy.
1. Great Barrel: You’ll need a premium match-grade barrel, well-machined with an excellent crown as well as a match-type chambering, true to the bore and well cut. The extension threads also needs to be cut true to the bore, with everything true as well as in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The common AR upper receiver is made for a lightweight carry rifle and they also stripped every one of the metal they can off it so it will be light to transport (which is advantageous for your military). The net result are upper receivers which can be so thin you can flex them your bare hands. These flexible uppers are “strong enough” for general use, however are not well suited for accuracy. Accuracy improves using a more rigid upper receiver.
3. True Receiver Face: We’ve learned that truing the receiver face is valuable. Some may argue this point however it is always wise to keep everything relevant to the barrel and also the bore in complete alignment using the bore (i.e. barrel extension, bolt, upper receiver, carrier, etc.).
4. Barrel Extension: You ought to Loctite or glue the barrel extension in to the upper receiver. This holds it in position entirely front to in the upper receiver. Otherwise if you find any play (where there typically is) it simply hangs about the face of your upper receiver completely dependent on your face in the upper receiver as the sole supply of support to the barrel instead of being made more a fundamental element of the top receiver when you are glued-in.
AR-X AR15 Upper5. Gas Block: You will want gas block that does not impose pointed stress in the barrel. Clamp-on types that grab all the way across the barrel are perfect. The blocks which can be pinned up with tapered pins that wedge versus the barrel or the slip on type of block with set screws that push up from underneath (or right on the barrel) can deform the bore within the barrel and will wreck the accuracy of an otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and i also emphasize the saying rigid) really is important. There are lots of forms of free-float handguards as well as a free-float handguard is, in and of itself, an enormous improvement more than a non-free-float create, but best is a rigid set-up. Some of the ones on the market are small diameter, thin or flexible and when you are shooting off any sort of rest, bipod, front bag, etc., a rigid fore-end is most beneficial since ARs wish to jump, bounce and twist once you let a try go, because the carrier starts to begin its cycle just before the bullet exits the bore.
7. Barrel Contour: You want some meat around the barrel. Between the upper receiver and also the gas block don’t go real thin by using a barrel (we love 1? diameter if it’s workable weight-wise). Once you touch off a round and the bullet passes the gas port, the gas system immediately starts pressuring up with a gas impulse which offers vibrations and stress in the barrel, especially involving the gas block returning to the receiver. A heavier barrel here dampens that. Staying a bit heavier with barrel contour from the gas block area and over to the muzzle is good for the same reasons. ARs have a lot going on when you touch off a round along with the gas system pressures up along with the carrier starts moving (all just before the bullet exits the bore) and so the more situations are made heavier and rigid to counteract the better – within reason (I’m not advocating a 12-lb barrel).
8. Gas Tube Routing Clearance: You need a gas tube that runs freely from the barrel nut, with the front of your upper receiver, and thru the gas key from the carrier. Ensure that the gas tube will not be impinged by some of them, to ensure that it does not load the carrier in the stressed orientation. You don’t want the gas tube bound up in order that if the gas tube pressures up it immediately would like to transmit more force and impulse on the barrel than would normally occur. We sometimes spend a 63dexjpky of time moving the gas block with gas tube off and on new build uppers and tweaking gas tubes to obtain proper clearance and alignment. Most gas tubes do need a little “tweaking” to have them right – factory tubes may work OK nevertheless they typically do not function optimally without hand-fitting.
9. Gas Port Tuning: You wish to avoid over-porting the gas port. Being over-gassed helps to make the gas system pressure up earlier and more aggressively. This will cause more impulse, and increases forces and vibration affecting the best end and also the barrel. Tune the gas port to give the level of pressure required to function properly and adequately but forget about.
10. Front/Back Bolt Play: If accuracy is definitely the game, don’t leave lots of front/back bolt play (ensure that it stays .003? but a maximum of .005?). We’ve seen factory rifles run .012? to .015? play, which is OK if you have to leave room for grime and dirt within a military application. However, that volume of play is not really ideal for a higher-accuracy AR build. A lot of front/back bolt play allows rounds to be hammered to the chamber and re-formed within a non-consistent way, because they are loaded in to the chamber.
11. Component Quality: Use good parts from a reputable source and also be wary of “gun show specials”. All the parts will not be the same. Some are excellent, some usually are not so good, and a few aftermarket parts are simply just bad. Don’t forget to work with mil-spec-type carriers; by and large they may be excellent for an accuracy build. Also, keep in mind that just because a carrier says “National Match” or something else upon it does not necessarily mean it’s any better. Be suspicious of chrome-plated parts as the chrome plating may change the various components dimensionally and may also make it difficult to do hand-fitting for fit and performance.
12. Upper to lessen Fit: A good upper/lower fit helps. For fast and dirty fit enhancement, an Accu-Wedge within the rear helps a good deal. The greatest solution is to bed top of the to your specific lower to ensure the lower and upper, when together, tend to be more like one integral unit. To the upper receivers we produce, we attempt to find the specs as close as we can, but still fit the different lowers in the marketplace place.
13. Muzzle Attachments: Don’t screw up the muzzle (literally). Leave just as much metal on the barrel with the muzzle as you can. People prefer to thread the muzzle for the flash hider, suppressor, muzzle brake, as well as other attachment, however, if you truly want accuracy, leave all the metal as possible there. And, for those who have something that screws on, set it up in order that it can be used on and get it stay there without putting a great deal of torque and stress on it right where bullet exits the bore. If you are planning to thread the conclusion in the barrel, ensure it is concentric using the bore and make certain everything you screw on the website is as well. For many muzzle attachments, also be sure that the holes by which the bullet passes through are dead true towards the bore. Many aftermarket screw-on everything is not good that way. Whatever vents gas should vent symmetrically (i.e. if this vents left, it must vent equally right, and likewise, when it vents up, it must vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo can be a whole story itself, but loads which can be too hot typically shoot poorly in best AR15 accessories. If you want accuracy away from an AR-15, avoid overly hot loads. Shown below are test groups shot with four (4) different uppers, all with moderate loads. These four uppers all just about had exactly the same features and things done to them as explained in the following paragraphs, and they all shot great.