Inside our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts upon an AR can definitely affect accuracy – such as free-floating handguards, barrels, bolts, bolt carriers?” He wanted an honest, well-informed answer, not just sales pitches. Robert Whitley posted an extremely comprehensive response to this, depending on his experience building and testing a large number of AR-15 manufacturer. Robert runs AR-X Enterprises, which produces match-grade uppers for High Power competitors, tactical shooters, and varminters.
There are a lot of things that you can do to an AR to further improve consistent accuracy, and that i use the words “consistent accuracy” because consistency is a part of it (i.e. a lot of guns will offer a couple of great 5-shot groups, but won’t do a very good 10- or 20-shot groups, and several guns will shoot great some day instead of so excellent on others).
Listed here are 14 key things we think are important to accuracy.
1. Great Barrel: You’ll desire a premium match-grade barrel, well-machined with a good crown as well as a match-type chambering, true to the bore and well cut. The extension threads must also be cut true on the bore, with everything true and then in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The normal AR upper receiver is made to get a lightweight carry rifle and they stripped every one of the metal they can off it making it light to handle (that is advantageous for your military). The net result are upper receivers which can be so thin you may flex them with your bare hands. These flexible uppers are “strong enough” for general use, but they are not ideal for accuracy. Accuracy improves by using a more rigid upper receiver.
3. True Receiver Face: We’ve found out that truing the receiver face is valuable. Some may argue this aspect yet it is always best to keep everything associated with the barrel along with the bore in complete alignment with all the bore (i.e. barrel extension, bolt, upper receiver, carrier, etc.).
4. Barrel Extension: You need to Loctite or glue the barrel extension to the upper receiver. This holds it set up entirely front to during the upper receiver. Otherwise if you find any play (there typically is) it really hangs in the face of your upper receiver completely dependent on the facial area in the upper receiver as being the sole supply of support for the barrel as opposed to being made more an important part of the top receiver by being glued-in.
AR-X AR15 Upper5. Gas Block: You desire a gas block that fails to impose pointed stress on the barrel. Clamp-on types that grab completely across the barrel are excellent. The blocks that are pinned up with tapered pins that wedge up against the barrel or maybe the slip on kind of block with set screws that push up from underneath (or entirely on the barrel) can deform the bore within the barrel and can wreck the accuracy of any otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and so i emphasize the phrase rigid) really is important. There are lots of kinds of free-float handguards plus a free-float handguard is, in and also of itself, a huge improvement more than a non-free-float setup, but best is a rigid set-up. Several of the ones out there are small diameter, thin and flexible and when you are shooting off any kind of rest, bipod, front bag, etc., a rigid fore-end is most beneficial since ARs want to jump, bounce and twist once you let a shot go, because the carrier actually starts to begin its cycle ahead of the bullet exits the bore.
7. Barrel Contour: You would like some meat in the barrel. Between your upper receiver as well as the gas block don’t go real thin by using a barrel (we love to 1? diameter if it’s workable weight-wise). If you touch off a round along with the bullet passes the gas port, the gas system immediately starts pressuring track of a gas impulse that gives vibrations and stress in the barrel, especially between the gas block straight back to the receiver. A heavier barrel here dampens that. Staying a bit heavier with barrel contour through the gas block area and over to the muzzle is good for exactly the same reasons. ARs have a lot occurring whenever you touch off a round along with the gas system pressures up along with the carrier starts moving (all ahead of the bullet exits the bore) therefore the more the situation is made heavier and rigid to counteract the better – within reason (I’m not advocating a 12-lb barrel).
8. Gas Tube Routing Clearance: You will want gas tube that runs freely with the barrel nut, through the front of the upper receiver, and thru the gas key inside the carrier. Ensure the gas tube will not be impinged by some of them, so that it does not load the carrier inside a stressed orientation. You don’t want the gas tube bound up to ensure if the gas tube pressures up it immediately wishes to transmit more force and impulse to the barrel than would normally occur. We sometimes spend a 63dexjpky of your time moving the gas block with gas tube off and on new build uppers and tweaking gas tubes to get proper clearance and alignment. Most gas tubes do need a little “tweaking” to obtain them right – factory tubes may work OK nevertheless they typically usually do not function optimally without hand-fitting.
9. Gas Port Tuning: You would like to avoid over-porting the gas port. Being over-gassed helps to make the gas system pressure up earlier and more aggressively. This causes 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 needed to function properly and adequately but no longer.
10. Front/Back Bolt Play: If accuracy may be 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, that is OK if you wish to leave room for dirt and grime within a military application. However, that volume of play will not be perfect for a higher-accuracy AR build. Lots of front/back bolt play allows rounds to get hammered in the chamber and in reality re-formed within a non-consistent way, since they are loaded into the chamber.
11. Component Quality: Use good parts from the reputable source and become cautious about “gun show specials”. All parts are certainly not a similar. Some are excellent, some are not so excellent, and a few aftermarket parts are merely bad. Don’t hesitate to make use of mil-spec-type carriers; in general these are good for an accuracy build. Also, do not forget that simply because a carrier says “National Match” or something that is else into it does not necessarily mean it’s any better. Be skeptical of chrome-plated parts as being the chrome plating can alter the various components dimensionally and may also allow it to be hard to do hand-fitting for fit and function.
12. Upper to decrease Fit: An excellent upper/lower fit is useful. For fast and dirty fit enhancement, an Accu-Wedge within the rear helps a good deal. The best solution is to sleep the top to a specific lower so that the lower and upper, when together, are definitely more like one integral unit. For your upper receivers we produce, we try to obtain the specs as close while we can, but nevertheless fit the various lowers in the marketplace place.
13. Muzzle Attachments: Don’t screw up the muzzle (literally). Leave the maximum amount of metal about the barrel with the muzzle as possible. People want to thread the muzzle to get a flash hider, suppressor, muzzle brake, as well as other attachment, but when you really want accuracy, leave just as much metal as you can there. And, when you have an issue that screws on, set it up up so it may be placed on and possess it stay there without putting a great deal of torque and stress on it right where bullet exits the bore. If you are intending to thread the conclusion of the barrel, ensure it is concentric together with the bore and ensure the things you screw on the website is just as well. For all those muzzle attachments, also be sure that the holes through which the bullet passes through are dead true for the bore. Many aftermarket screw-on everything is not too good that way. Something that vents gas should vent symmetrically (i.e. if it vents left, it ought to vent equally right, and likewise, when it vents up, it ought to vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo can be a whole story on its own, but loads which are too hot typically shoot poorly in cheap AR15 uppers for sale. If you need 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 basically had the identical features and things performed to them as explained in this article, and they also all shot great.