In our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts upon an AR can definitely affect accuracy – including free-floating handguards, barrels, bolts, bolt carriers?” He wanted a genuine, well-informed answer, not simply sales pitches. Robert Whitley posted a really comprehensive response to this, based upon his experience building and testing a large number of cheap AR15 uppers for sale. Robert runs AR-X Enterprises, which produces match-grade uppers for top Power competitors, tactical shooters, and varminters.
There are a lot of things that you can do with an AR to enhance consistent accuracy, and i also make use of the words “consistent accuracy” because consistency is an integral part of it (i.e. a lot of guns will provide a few great 5-shot groups, but won’t do a really good 10- or 20-shot groups, plus some guns will shoot great one day instead of so excellent on others).
Listed below are 14 key things we believe are essential to accuracy.
1. Great Barrel: You’ll need a premium match-grade barrel, well-machined with an excellent crown and a match-type chambering, true on the bore and well cut. The extension threads should also be cut true for the bore, with everything else true and then in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The standard AR upper receiver was created for any lightweight carry rifle and so they stripped all of the metal they might off it to really make it light to carry (which can be advantageous for that military). The web 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 they are not well suited for accuracy. Accuracy improves with 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 using the bore (i.e. barrel extension, bolt, upper receiver, carrier, etc.).
4. Barrel Extension: You should Loctite or glue the barrel extension to the upper receiver. This holds it in position completely front to back in the upper receiver. Otherwise if you find any play (and there typically is) it simply hangs in the face from the upper receiver completely dependent on your face of your upper receiver since the sole source of support for your barrel as opposed to being made more a fundamental element of the upper receiver when you are glued-in.
AR-X AR15 Upper5. Gas Block: You will want gas block that will 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 up against the barrel or maybe 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 can wreck the precision of your otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and I emphasize the word rigid) really is important. There are numerous kinds of free-float handguards and a free-float handguard is, in and also itself, an enormous improvement more than a non-free-float create, but best is actually a rigid set-up. Several of the ones on the market are small diameter, thin and flexible and in case you are shooting off any kind of rest, bipod, front bag, etc., a rigid fore-end is best since ARs desire to jump, bounce and twist if you let an attempt go, as being the carrier starts to begin its cycle prior to the bullet exits the bore.
7. Barrel Contour: You desire some meat on the barrel. Between the upper receiver along with the gas block don’t go real thin using a barrel (we love 1? diameter if it’s workable weight-wise). If you touch off a round and the bullet passes the gas port, the gas system immediately starts pressuring on top of a gas impulse that offers vibrations and stress on the barrel, especially involving the gas block returning to the receiver. A heavier barrel here dampens that. Staying a bit heavier with barrel contour throughout the gas block area and in the market to the muzzle will work for the identical reasons. ARs have a lot occurring once you touch off a round and the gas system pressures up and the carrier starts moving (all just before the bullet exits the bore) so the more the situation 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 need a gas tube that runs freely from the barrel nut, through the front of the upper receiver, and through the gas key within the carrier. Guarantee the gas tube is just not impinged by any of them, to ensure that it fails to load the carrier inside a stressed orientation. You don’t want the gas tube bound up so that once the gas tube pressures up it immediately would like to transmit more force and impulse for 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 obtain proper clearance and alignment. Most gas tubes do need a little “tweaking” to have them right – factory tubes may work OK but they typically tend not to function optimally without hand-fitting.
9. Gas Port Tuning: You would like to avoid over-porting the gas port. Being over-gassed definitely makes the gas system pressure up earlier and a lot more aggressively. This leads to more impulse, and increases forces and vibration affecting the best end and also the barrel. Tune the gas port to provide the quantity of pressure necessary to function properly and adequately but no more.
10. Front/Back Bolt Play: If accuracy is definitely the game, don’t leave a great deal of front/back bolt play (keep it .003? but not 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 in the military application. However, that level of play is just not ideal for a high-accuracy AR build. Lots of front/back bolt play allows rounds to get hammered in the chamber and in reality re-formed in a non-consistent way, as they are loaded to the chamber.
11. Component Quality: Use good parts from a reputable source and stay wary of “gun show specials”. All the parts usually are not the identical. Some are good, some will not be so excellent, and a few aftermarket parts are just bad. Don’t be afraid to work with mil-spec-type carriers; in general they are good for an accuracy build. Also, keep in mind that just because a carrier says “National Match” or something else onto it does not always mean it’s any better. Be wary of chrome-plated parts because the chrome plating may change the various components dimensionally and might also ensure it is difficult to do hand-fitting for fit and performance.
12. Upper to reduce Fit: A good upper/lower fit helps. For quick and dirty fit enhancement, an Accu-Wedge in the rear helps a whole lot. The best option would be to sleep the top to your specific lower so the lower and upper, when together, are definitely more like one integral unit. For your upper receivers we produce, we try to find the specs as near when we can, but nevertheless fit the various lowers in the market place.
13. Muzzle Attachments: Don’t screw in the muzzle (literally). Leave just as much metal around the barrel with the muzzle since you can. People like to thread the muzzle for any flash hider, suppressor, muzzle brake, or some other attachment, but if you truly want accuracy, leave the maximum amount of metal since you can there. And, when you have an issue that screws on, set it up so it can be used on and also have 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 final of your barrel, make it concentric together with the bore and be sure the things you screw on the website can be as well. For all muzzle attachments, also ensure that the holes by which the bullet passes through are dead true towards the bore. Many aftermarket screw-on things are not so good like that. Something that vents gas should vent symmetrically (i.e. if this vents left, it ought to vent equally right, and likewise, if it vents up, it should vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo is actually a whole story by itself, but loads that happen to be too hot typically shoot poorly in best AR15 stock. If you want accuracy from an AR-15, avoid overly hot loads. Shown here are test groups shot with four (4) different uppers, all with moderate loads. These four uppers all basically had the same features and things completed to them as explained in this article, and so they all shot great.