Within our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts with an AR really can affect accuracy – like free-floating handguards, barrels, bolts, bolt carriers?” He wanted a sincere, well-informed answer, not just sales pitches. Robert Whitley posted a very comprehensive reply to this query, according to his experience building and testing many AR-15 manufacturers. Robert runs AR-X Enterprises, which produces match-grade uppers for top Power competitors, tactical shooters, and varminters.
There are plenty of things that you can do 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 provide a couple great 5-shot groups, but won’t do a good 10- or 20-shot groups, and a few guns will shoot great a day and not so great on others).
Listed here are 14 key things we think are crucial to accuracy.
1. Great Barrel: You’ll desire a premium match-grade barrel, well-machined with a great crown and a match-type chambering, true for the bore and well cut. The extension threads also must be cut true on the bore, with everything else true and then in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The normal AR upper receiver was made for a lightweight carry rifle and they also stripped all the metal they can off it to make it light to transport (which can be advantageous for your military). The world wide web result are upper receivers that are so thin you are able 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 with a more rigid upper receiver.
3. True Receiver Face: We’ve discovered that truing the receiver face is valuable. Some may argue this time however 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 in to the upper receiver. This holds it in place completely front to during the upper receiver. Otherwise when there is any play (and there typically is) it really hangs about the face from the upper receiver completely influenced by your face of your upper receiver as being the sole supply of support for that 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 desire a gas block that will not impose pointed stress about the barrel. Clamp-on types that grab entirely across the barrel are fantastic. The blocks that are pinned on with tapered pins that wedge versus the barrel or even the slip on sort of block with set screws that push up from underneath (or entirely on the barrel) can deform the bore inside the barrel and can wreck the accuracy of an 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 numerous varieties of free-float handguards as well as a free-float handguard is, in and also itself, a massive improvement spanning a non-free-float set up, but best is really a rigid set-up. A number of the ones available on the market are small diameter, thin and/or flexible and if you are shooting off almost any rest, bipod, front bag, etc., a rigid fore-end is better since ARs want to jump, bounce and twist once you let a shot go, since the carrier actually starts to begin its cycle prior to the bullet exits the bore.
7. Barrel Contour: You desire some meat on the barrel. Involving the upper receiver and the gas block don’t go real thin with a barrel (we love 1? diameter if it’s workable weight-wise). Whenever you touch off a round and the bullet passes the gas port, the gas system immediately starts pressuring with a gas impulse which offers vibrations and stress around the barrel, especially between your gas block returning to the receiver. A heavier barrel here dampens that. Staying a little heavier with barrel contour with the gas block area and out to the muzzle is useful for exactly the same reasons. ARs possess a lot going on once you touch off a round and also the gas system pressures up as well as the carrier starts moving (all ahead of the bullet exits the bore) so the more everything is made heavier and rigid to counteract that 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 through the barrel nut, throughout the front in the upper receiver, and thru the gas key in the carrier. Ensure the gas tube is just not impinged by any of them, to ensure that it will not load the carrier inside a stressed orientation. You don’t want the gas tube bound up to ensure when the gas tube pressures up it immediately desires to transmit more force and impulse on 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 get proper clearance and alignment. Most gas tubes do need some “tweaking” to get them right – factory tubes may work OK nevertheless they typically 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 a lot more aggressively. This will cause more impulse, and increases forces and vibration affecting the top end along with the barrel. Tune the gas port to provide the amount of pressure found it necessary to function properly and adequately but forget about.
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 no more than .005?). We’ve seen factory rifles run .012? to .015? play, that is OK if you need to leave room for dirt and grime in a military application. However, that level of play is not really well suited for a very high-accuracy AR build. Lots of front/back bolt play allows rounds to get hammered into the chamber and in reality re-formed in the non-consistent way, since they are loaded into the chamber.
11. Component Quality: Use good parts coming from a reputable source and also be wary of “gun show specials”. All parts are certainly not the same. Some are good, some usually are not so great, plus some aftermarket parts are simply bad. Don’t forget to make use of mil-spec-type carriers; in general they may be good for an accuracy build. Also, remember that simply because a carrier says “National Match” or something else on it does not always mean it’s any better. Be suspicious of chrome-plated parts as the chrome plating may change the various components dimensionally and might also allow it to be difficult to do hand-fitting for fit and performance.
12. Upper to reduce Fit: An effective upper/lower fit is effective. For quick and dirty fit enhancement, an Accu-Wedge within the rear helps a great deal. The greatest option is to bed top of the into a specific lower in order that the upper and lower, when together, will be more like one integral unit. To the upper receivers we produce, we attempt to get the specs as near when we can, yet still fit the many lowers in the marketplace place.
13. Muzzle Attachments: Don’t screw the muzzle (literally). Leave just as much metal about the barrel at the muzzle as possible. People love to thread the muzzle for the flash hider, suppressor, muzzle brake, or some other attachment, however, if you really want accuracy, leave as much metal that you can there. And, if you have a thing that screws on, set it up in order that it can be put on and also have it stay there without putting a great deal of torque and stress upon it right the location where the bullet exits the bore. If you are intending to thread the final of your barrel, allow it to be concentric with the bore and be sure everything you screw on the website is 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 everything is less than good that way. Something that vents gas should vent symmetrically (i.e. if it vents left, it must vent equally right, and likewise, when it vents up, it must vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo is a whole story itself, but loads that happen to be too hot typically shoot poorly in AR15 accessories. If you want accuracy away from 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 virtually had exactly the same features and things carried out to them as explained in the following paragraphs, plus they all shot great.