Within our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts on an AR can really 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 query, depending on his experience building and testing lots of AR15 forward assist. Robert runs AR-X Enterprises, which produces match-grade uppers for High Power competitors, tactical shooters, and varminters.
There are tons of things that can be done to a AR to improve consistent accuracy, and that i take advantage of the words “consistent accuracy” because consistency is a part of it (i.e. lots of guns can give several great 5-shot groups, but won’t do an excellent 10- or 20-shot groups, and several guns will shoot great 1 day and not so good on others).
Here are 14 key things we think are important to accuracy.
1. Great Barrel: You’ll need a premium match-grade barrel, well-machined with a decent crown and a match-type chambering, true towards the bore and well cut. The extension threads also needs to be cut true for the bore, with everything else true as well as in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The standard AR upper receiver was developed for any lightweight carry rifle and they also stripped each of the metal they could off it making it light to hold (which can be advantageous for your military). The web result are upper receivers which can be so thin it is possible to flex them your bare hands. These flexible uppers are “strong enough” for general use, however they are not well suited for accuracy. Accuracy improves 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 point yet it is always wise to keep everything linked to the barrel along with 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 into the upper receiver. This holds it set up completely front to in the upper receiver. Otherwise if you have any play (where there typically is) it just hangs about the face of the upper receiver completely influenced by the facial area of the upper receiver because the sole method to obtain support for that barrel rather than being made more a fundamental element of the upper receiver by being glued-in.
AR-X AR15 Upper5. Gas Block: You want a gas block that fails to impose pointed stress on the barrel. Clamp-on types that grab all the way up across the barrel are fantastic. The blocks which can be pinned up with tapered pins that wedge against the barrel or even the slip on sort of block with set screws that push up from underneath (or right on the barrel) can deform the bore within the barrel and may wreck the precision of an otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and so i emphasize the phrase rigid) really makes a difference. There are numerous forms of free-float handguards plus a free-float handguard is, in and of itself, a tremendous improvement over a non-free-float put in place, but best is actually a rigid set-up. Several of the ones on the market are small diameter, thin and flexible and if you are shooting off any kind of rest, bipod, front bag, etc., a rigid fore-end is better since ARs want to jump, bounce and twist when you let an attempt go, since the carrier actually starts to begin its cycle prior to the bullet exits the bore.
7. Barrel Contour: You would like some meat on the barrel. Involving the upper receiver and the gas block don’t go real thin having a barrel (we love 1? diameter if it’s workable weight-wise). When you touch off a round and also the bullet passes the gas port, the gas system immediately starts pressuring with a gas impulse that offers vibrations and stress in the barrel, especially between the gas block to the receiver. A heavier barrel here dampens that. Staying a bit heavier with barrel contour through the gas block area and in the market to the muzzle is useful for a similar reasons. ARs have a lot happening when you touch off a round along with the gas system pressures up as well as the carrier starts moving (all prior to the bullet exits the bore) therefore the more everything is made heavier and rigid to counteract that this better – within reason (I’m not advocating a 12-lb barrel).
8. Gas Tube Routing Clearance: You will want gas tube that runs freely through the barrel nut, with the front of your upper receiver, and thru the gas key within the carrier. Ensure the gas tube is not impinged by any kind of them, in order that it does not load the carrier inside a stressed orientation. You don’t want the gas tube bound up so that when 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 energy 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 acquire them right – factory tubes may work OK but 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 make the gas system pressure up earlier and much more aggressively. This will cause more impulse, and increases forces and vibration affecting the most notable end along with the barrel. Tune the gas port to provide the quantity of pressure needed to function properly and adequately but forget about.
10. Front/Back Bolt Play: If accuracy may be the game, don’t leave a lot of front/back bolt play (ensure that it stays .003? but no more than .005?). We’ve seen factory rifles run .012? to .015? play, which is OK if you want to leave room for grime and dirt in the military application. However, that level of play is not ideal for a very high-accuracy AR build. A lot of front/back bolt play allows rounds to become hammered in to the chamber and also re-formed within a non-consistent way, because they are loaded in to the chamber.
11. Component Quality: Use good parts from your reputable source and be cautious about “gun show specials”. All parts are certainly not the identical. Some are good, some usually are not so excellent, and a few aftermarket parts are just bad. Don’t hesitate to make use of mil-spec-type carriers; in general these are excellent for an accuracy build. Also, understand that just because a carrier says “National Match” or anything else into it does not always mean it’s any better. Be skeptical of chrome-plated parts since the chrome plating can transform the various components dimensionally and might also allow it to be hard to do hand-fitting for fit and performance.
12. Upper to reduce Fit: An excellent upper/lower fit is effective. For quick and dirty fit enhancement, an Accu-Wedge within the rear helps a great deal. The ultimate solution is to sleep the top into a specific lower so that the upper and lower, when together, are more like one integral unit. For your upper receivers we produce, we attempt to find the specs as near while we can, but nevertheless fit the different lowers in the market place.
13. Muzzle Attachments: Don’t screw the muzzle (literally). Leave all the metal in the barrel at the muzzle that you can. People prefer to thread the muzzle for the flash hider, suppressor, muzzle brake, as well as other attachment, but if you really want accuracy, leave just as much metal as possible there. And, in case you have an issue that screws on, set it up up to ensure that it may be placed on and possess it stay there without putting lots of torque and stress upon it right where bullet exits the bore. If you are planning to thread the final of the barrel, make it concentric with all the bore and make certain whatever you screw on the website is really as well. For those muzzle attachments, also ensure that the holes through which the bullet passes through are dead true towards the bore. Many aftermarket screw-on situations are less than good that way. Anything that vents gas should vent symmetrically (i.e. if this vents left, it must vent equally right, and likewise, when it vents up, it should vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo can be a whole story itself, but loads that are too hot typically shoot poorly in best AR 15 brands. 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 same features and things carried out to them as explained on this page, plus they all shot great.