In our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts upon an AR can definitely affect accuracy – for example free-floating handguards, barrels, bolts, bolt carriers?” He wanted a genuine, well-informed answer, not merely sales pitches. Robert Whitley posted an incredibly comprehensive solution to this query, according to his experience building and testing dozens of top AR 15 manufacturers. Robert runs AR-X Enterprises, which produces match-grade uppers for High Power competitors, tactical shooters, and varminters.
There are tons of things that you can do for an AR to improve consistent accuracy, and I use the words “consistent accuracy” because consistency is an integral part of it (i.e. plenty of guns can give a few great 5-shot groups, but won’t do a really good 10- or 20-shot groups, and a few guns will shoot great a day and not so excellent on others).
Listed below are 14 key things we think are crucial to accuracy.
1. Great Barrel: You’ll require a premium match-grade barrel, well-machined with an excellent crown as well as a match-type chambering, true towards the bore and well cut. The extension threads also must be cut true on the bore, with everything true as well as in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The standard AR upper receiver is made to get a lightweight carry rifle plus they stripped all the metal they might off it so it will be light to transport (which happens to be advantageous for the military). The internet result are upper receivers which are so thin you can flex them your bare hands. These flexible uppers are “strong enough” for general use, but 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 aspect but it is always advisable to keep everything associated with the barrel and the bore in complete alignment with the bore (i.e. barrel extension, bolt, upper receiver, carrier, etc.).
4. Barrel Extension: You must Loctite or glue the barrel extension in the upper receiver. This holds it set up completely front to in the upper receiver. Otherwise if you find any play (where there typically is) it just hangs about the face in the upper receiver completely determined by your face of your upper receiver as the sole supply of support to the barrel instead of being made more a fundamental part of the upper receiver when you are glued-in.
AR-X AR15 Upper5. Gas Block: You need a gas block that does not impose pointed stress around the barrel. Clamp-on types that grab completely across the barrel are excellent. The blocks which can be pinned up with tapered pins that wedge from the barrel or maybe the slip on type of block with set screws that push up from underneath (or right on the barrel) can deform the bore inside the barrel and will wreck the precision of your otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and i also emphasize the phrase rigid) really is important. There are many types of free-float handguards plus a free-float handguard is, in and of itself, a huge improvement over a non-free-float setup, but best can be a rigid set-up. A few of the ones available on the market are small diameter, thin and/or flexible and when you are shooting off any kind of rest, bipod, front bag, etc., a rigid fore-end is best since ARs want to jump, bounce and twist once you let an attempt go, because the carrier begins to begin its cycle ahead of the bullet exits the bore.
7. Barrel Contour: You need some meat around the barrel. In between the upper receiver as well as the gas block don’t go real thin with a barrel (we like 1? diameter if it’s workable weight-wise). Whenever you touch off a round and also the bullet passes the gas port, the gas system immediately starts pressuring on top of a gas impulse that provides vibrations and stress around the barrel, especially between your gas block back to the receiver. A heavier barrel here dampens that. Staying a little heavier with barrel contour throughout the gas block area and to the muzzle is perfect for exactly the same reasons. ARs possess a lot taking place if you touch off a round and also the gas system pressures up and also the carrier starts moving (all before the bullet exits the bore) hence the more everything is made heavier and rigid to counteract how the better – within reason (I’m not advocating a 12-lb barrel).
8. Gas Tube Routing Clearance: You desire a gas tube that runs freely through the barrel nut, with the front from the upper receiver, and through the gas key inside the carrier. Ensure the gas tube will not be impinged by any kind of them, so it fails to load the carrier within a stressed orientation. You don’t want the gas tube bound up so that if the gas tube pressures up it immediately wishes to transmit more force and impulse on the barrel than would normally occur. We sometimes spend a 63dexjpky of your energy moving the gas block with gas tube on and off new build uppers and tweaking gas tubes to acquire proper clearance and alignment. Most gas tubes do need a little “tweaking” to obtain them right – factory tubes may work OK however they typically tend not to function optimally without hand-fitting.
9. Gas Port Tuning: You want to avoid over-porting the gas port. Being over-gassed makes the gas system pressure up earlier and much more aggressively. This leads to more impulse, and increases forces and vibration affecting the top end and the barrel. Tune the gas port to provide the amount of pressure found it necessary to function properly and adequately but no longer.
10. Front/Back Bolt Play: If accuracy is definitely 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 have to leave room for grime and dirt inside a military application. However, that level of play is not really perfect for a higher-accuracy AR build. Lots of front/back bolt play allows rounds to become hammered in to the chamber and also re-formed inside a non-consistent way, because they are loaded in the chamber.
11. Component Quality: Use good parts coming from a reputable source and become cautious about “gun show specials”. All the parts are certainly not exactly the same. Some are good, some will not be so excellent, and some aftermarket parts are just bad. Don’t be afraid to make use of mil-spec-type carriers; in general these are excellent for an accuracy build. Also, do not forget that simply because a carrier says “National Match” or anything else on it does not necessarily mean it’s any better. Be suspicious of chrome-plated parts since the chrome plating can transform the parts dimensionally and can also allow it to be difficult to do hand-fitting for fit and function.
12. Upper to reduce Fit: An excellent upper/lower fit is helpful. For fast and dirty fit enhancement, an Accu-Wedge within the rear helps a good deal. The best option would be to sleep the upper to your specific lower so that the lower and upper, when together, will be more like one integral unit. For your upper receivers we produce, we try to have the specs as near as we can, but still fit the various lowers on the market place.
13. Muzzle Attachments: Don’t screw up the muzzle (literally). Leave as much metal about the barrel in the muzzle as possible. People love to thread the muzzle for a flash hider, suppressor, muzzle brake, or some other attachment, however, if you want accuracy, leave all the metal as possible there. And, if you have something which screws on, set it up so it may be put on and have it stay there without putting plenty of torque and stress upon it right where the bullet exits the bore. If you are going to thread the final in the barrel, allow it to be concentric using the bore and ensure the things you screw on there is just as well. For all muzzle attachments, also ensure that the holes whereby the bullet passes through are dead true to the bore. Many aftermarket screw-on the situation is not so good doing this. Anything that vents gas should vent symmetrically (i.e. when 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 actually a whole story on its own, but loads which can be too hot typically shoot poorly in top AR15 manufacturers. If you wish accuracy out of an AR-15, avoid overly hot loads. Shown listed below are test groups shot with four (4) different uppers, all with moderate loads. These four uppers all just about had the identical features and things carried out to them as explained on this page, and so they all shot great.