In our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts with an AR really can affect accuracy – such as free-floating handguards, barrels, bolts, bolt carriers?” He wanted a genuine, well-informed answer, not merely sales pitches. Robert Whitley posted an incredibly comprehensive response to this inquiry, based on his experience building and testing lots of AR complete upper. 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 enhance consistent accuracy, and I use the words “consistent accuracy” because consistency is an integral part of it (i.e. plenty of guns will offer a couple great 5-shot groups, but won’t do a really good 10- or 20-shot groups, plus some guns will shoot great 1 day instead of so excellent on others).
Listed below are 14 key things we believe are essential to accuracy.
1. Great Barrel: You’ll desire a premium match-grade barrel, well-machined with an excellent crown as well as a match-type chambering, true for the bore and well cut. The extension threads also must be cut true to the bore, with everything else true and then in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The common AR upper receiver is made for the lightweight carry rifle and they stripped all of the metal they might off it to really make it light to handle (which can be advantageous for your military). The net result are upper receivers that happen to be so thin you are able to flex them your bare hands. These flexible uppers are “strong enough” for general use, but are not ideal for accuracy. Accuracy improves having a more rigid upper receiver.
3. True Receiver Face: We’ve discovered that truing the receiver face is valuable. Some may argue this aspect but it is always wise to keep everything associated with the barrel as well as the bore in complete alignment with all the bore (i.e. barrel extension, bolt, upper receiver, carrier, etc.).
4. Barrel Extension: You must Loctite or glue the barrel extension into the upper receiver. This holds it in place entirely front to during the upper receiver. Otherwise when there is any play (and there typically is) it just hangs in the face of your upper receiver completely determined by the face from the upper receiver since the sole method to obtain support to the barrel as opposed to being made more an integral part of top of the receiver when you are glued-in.
AR-X AR15 Upper5. Gas Block: You need a gas block that fails to impose pointed stress in the barrel. Clamp-on types that grab completely throughout the barrel are fantastic. The blocks which are pinned up with tapered pins that wedge versus the barrel or perhaps the slip on type of block with set screws that push up from underneath (or entirely on the barrel) can deform the bore inside the barrel and may wreck the accuracy of an otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and I emphasize the term rigid) really makes a difference. There are numerous kinds of free-float handguards as well as a free-float handguard is, in and also itself, a massive improvement over a non-free-float create, but best is really a rigid set-up. Some of the ones out there are small diameter, thin and/or flexible and should you be shooting off any sort of rest, bipod, front bag, etc., a rigid fore-end is most beneficial since ARs want to jump, bounce and twist if you let a go go, since the carrier starts to begin its cycle prior to the bullet exits the bore.
7. Barrel Contour: You desire some meat about the barrel. Involving the upper receiver and the gas block don’t go real thin using a barrel (we love to 1? diameter if it’s workable weight-wise). Whenever you touch off a round along with the bullet passes the gas port, the gas system immediately starts pressuring up with a gas impulse that offers vibrations and stress around the barrel, especially in between the gas block back to the receiver. A heavier barrel here dampens that. Staying a little bit heavier with barrel contour with the gas block area and over to the muzzle is good for the same reasons. ARs possess a lot happening if you touch off a round and also the gas system pressures up along with the carrier starts moving (all ahead of the bullet exits the bore) therefore the more things are 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 need a gas tube that runs freely throughout the barrel nut, throughout the front of the upper receiver, and through the gas key from the carrier. Make sure the gas tube will not be impinged by some of them, so it is not going to load the carrier within a stressed orientation. You don’t want the gas tube bound up to ensure that 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 energy moving the gas block with gas tube on / off new build uppers and tweaking gas tubes to have proper clearance and alignment. Most gas tubes do need some “tweaking” to acquire them right – factory tubes may work OK nonetheless they typically do not function optimally without hand-fitting.
9. Gas Port Tuning: You want to avoid over-porting the gas port. Being over-gassed definitely makes the gas system pressure up earlier and a lot more aggressively. This causes more impulse, and increases forces and vibration affecting the very best end along with the barrel. Tune the gas port to provide the amount of pressure necessary to function properly and adequately but no more.
10. Front/Back Bolt Play: If accuracy is the game, don’t leave a great deal of front/back bolt play (ensure that it stays .003? but at most .005?). We’ve seen factory rifles run .012? to .015? play, that is OK if you wish to leave room for grime and dirt in the military application. However, that quantity of play is not perfect for a high-accuracy AR build. A great deal of front/back bolt play allows rounds to get hammered in the chamber and re-formed in a non-consistent way, because they are loaded in to the chamber.
11. Component Quality: Use good parts from your reputable source and stay wary of “gun show specials”. All the parts usually are not exactly the same. Some are good, some are not so excellent, and some aftermarket parts are simply just bad. Don’t forget to use mil-spec-type carriers; generally they are excellent for an accuracy build. Also, remember that even though a carrier says “National Match” or anything else on it does not necessarily mean it’s any better. Be suspicious of chrome-plated parts because the chrome plating can change the various components dimensionally and can also make it hard to do hand-fitting for fit and function.
12. Upper to decrease Fit: A great upper/lower fit is helpful. For quick and dirty fit enhancement, an Accu-Wedge from the rear helps a good deal. The greatest option is to sleep top of the to a specific lower so that the lower and upper, when together, are more like one integral unit. For your upper receivers we produce, we try to get the specs as close since we can, but nevertheless fit the various lowers available in the market place.
13. Muzzle Attachments: Don’t screw up the muzzle (literally). Leave the maximum amount of metal on the barrel in the muzzle as possible. People like to thread the muzzle for any flash hider, suppressor, muzzle brake, or some other attachment, but if you really want accuracy, leave all the metal as possible there. And, for those who have an issue that screws on, set it up in order that it can be put on and have it stay there without putting plenty of torque and stress onto it right where the bullet exits the bore. If you are planning to thread the conclusion from the barrel, allow it to be concentric with all the bore and be sure what you screw on there is just as well. For all those muzzle attachments, also be sure that the holes by which the bullet passes through are dead true on the bore. Many aftermarket screw-on the situation is less than good doing this. Something that vents gas should vent symmetrically (i.e. if it vents left, it should 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 is really a whole story itself, but loads that happen to be too hot typically shoot poorly in AR-15 manufacturers. If you wish accuracy out 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 virtually had the identical features and things performed to them as explained in the following paragraphs, and they all shot great.