In your Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts upon an AR can actually affect accuracy – for example free-floating handguards, barrels, bolts, bolt carriers?” He wanted a truthful, well-informed answer, not merely sales pitches. Robert Whitley posted a very comprehensive solution to this question, according to his experience building and testing dozens of best AR 15 brands. Robert runs AR-X Enterprises, which produces match-grade uppers for top Power competitors, tactical shooters, and varminters.
There are tons of things which can be done for an AR to boost consistent accuracy, and that i use the words “consistent accuracy” because consistency is an integral part of it (i.e. plenty of guns will give a couple great 5-shot groups, but won’t do a good 10- or 20-shot groups, and several guns will shoot great a day rather than so great on others).
Listed here are 14 key things we believe are crucial to accuracy.
1. Great Barrel: You’ll require a premium match-grade barrel, well-machined with a great crown as well as a match-type chambering, true for the bore and well cut. The extension threads should also be cut true towards the bore, with everything true and then in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The common AR upper receiver was developed for the lightweight carry rifle and so they stripped all the metal they can off it so it will be light to hold (which is advantageous for your military). The web result are upper receivers which are so thin it is possible to flex all of them with your bare hands. These flexible uppers are “strong enough” for general use, however they are not perfect 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 yet it is always better to keep everything associated with 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 must Loctite or glue the barrel extension in to the upper receiver. This holds it into position completely front to in the upper receiver. Otherwise if you have any play (where there typically is) it merely hangs about the face in the upper receiver completely influenced by your face of the upper receiver because the sole source of support for your barrel rather than being made more a fundamental element of the top receiver when you are glued-in.
AR-X AR15 Upper5. Gas Block: You need a gas block that does not impose pointed stress about the barrel. Clamp-on types that grab all the way round the barrel are great. The blocks that are pinned up with tapered pins that wedge 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 inside of the barrel and may wreck the accuracy of any otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and that i emphasize the term rigid) really makes a difference. There are lots of types of free-float handguards plus a free-float handguard is, in and of itself, an enormous improvement over a non-free-float set up, but best is actually a rigid set-up. Several of the ones in the marketplace are small diameter, thin and/or flexible and in case 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 a try go, since the carrier begins to begin its cycle prior to the bullet exits the bore.
7. Barrel Contour: You would like some meat around the barrel. Between your upper receiver and also the gas block don’t go real thin having a barrel (we like 1? diameter if it’s workable weight-wise). When 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 gives vibrations and stress in the barrel, especially between your gas block returning 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 useful for exactly the same reasons. ARs possess a lot taking place if you touch off a round and also the gas system pressures up along with the carrier starts moving (all prior to the bullet exits the bore) and so the more things are 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 want a gas tube that runs freely from the barrel nut, with the front in the upper receiver, and through the gas key inside the carrier. Guarantee the gas tube is not impinged by any of them, so it will not load the carrier in a stressed orientation. You don’t want the gas tube bound up so that if the gas tube pressures up it immediately desires to transmit more force and impulse to the barrel than would normally occur. We sometimes spend a 63dexjpky of time moving the gas block with gas tube on and off new build uppers and tweaking gas tubes to get proper clearance and alignment. Most gas tubes do need a little “tweaking” to acquire them right – factory tubes may work OK however 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 plus more aggressively. This causes more impulse, and increases forces and vibration affecting the most notable end and also the barrel. Tune the gas port to provide the volume of pressure found it necessary to function properly and adequately but you can forget.
10. Front/Back Bolt Play: If accuracy is the game, don’t leave lots of front/back bolt play (ensure that it stays .003? but at most .005?). We’ve seen factory rifles run .012? to .015? play, which happens to be OK if you wish to leave room for grime and dirt in a military application. However, that volume of play is not ideal for a very high-accuracy AR build. A great deal of front/back bolt play allows rounds to be hammered in the chamber and actually re-formed inside a non-consistent way, since they are loaded in the chamber.
11. Component Quality: Use good parts from your reputable source and be wary of “gun show specials”. All parts are NOT exactly the same. Some are good, some are certainly not so excellent, and several aftermarket parts are just bad. Don’t be scared to work with mil-spec-type carriers; generally they are good for an accuracy build. Also, understand that even though a carrier says “National Match” or something that is else upon it does not always mean it’s any better. Be suspicious of chrome-plated parts as the chrome plating can transform the various components dimensionally and may also make it difficult to do hand-fitting for fit and performance.
12. Upper to Lower Fit: An excellent upper/lower fit is useful. For quick and dirty fit enhancement, an Accu-Wedge from the rear helps a good deal. The best solution is to sleep the upper into a specific lower in order that the lower and upper, when together, are definitely more like one integral unit. For that upper receivers we produce, we attempt to have the specs as near while we can, but nonetheless fit the different lowers on the market place.
13. Muzzle Attachments: Don’t screw up the muzzle (literally). Leave just as much metal around the barrel in the muzzle as you can. People love to thread the muzzle to get a flash hider, suppressor, muzzle brake, as well as other attachment, however, if you truly want accuracy, leave the maximum amount of metal as you can there. And, if you have something which screws on, set it up up to ensure that it may be put on and possess it stay there without putting a great deal of torque and stress onto it right in which the bullet exits the bore. If you are planning to thread the final of your barrel, make it concentric using the bore and ensure everything you screw on the website can be as well. For all those muzzle attachments, also be sure that the holes through which the bullet passes through are dead true to the bore. Many aftermarket screw-on situations are not so good doing this. Anything that vents gas should vent symmetrically (i.e. if it vents left, it must vent equally right, and likewise, whether it vents up, it ought to vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo is really a whole story by itself, but loads that happen to be too hot typically shoot poorly in AR-15 2 stage trigger. If you want accuracy away 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 just about had exactly the same features and things completed to them as explained in this article, and so they all shot great.