Inside our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts on an AR really can affect accuracy – including free-floating handguards, barrels, bolts, bolt carriers?” He wanted a genuine, well-informed answer, not simply sales pitches. Robert Whitley posted an extremely comprehensive response to this query, according to his experience building and testing lots of AR 15 complete upper receiver 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 further improve consistent accuracy, and that i use the words “consistent accuracy” because consistency is a part of it (i.e. plenty of guns can give a couple great 5-shot groups, but won’t do a very good 10- or 20-shot groups, and a few guns will shoot great a day instead of so great on others).
Listed here are 14 key things we think are essential to accuracy.
1. Great Barrel: You’ll want a premium match-grade barrel, well-machined with a good crown along with a match-type chambering, true to the bore and well cut. The extension threads also must be cut true on the bore, with everything else true as well as in proper alignment.
2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The normal AR upper receiver was developed to get a lightweight carry rifle and so they stripped every one of the metal they may off it to make it light to transport (which happens to be advantageous to the military). The world wide web result are upper receivers that happen to be so thin you may flex all of them with your bare hands. These flexible uppers are “strong enough” for general use, but are not ideal for accuracy. Accuracy improves by using a more rigid upper receiver.
3. True Receiver Face: We’ve learned that truing the receiver face is valuable. Some may argue this point however it is always best 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 ought to Loctite or glue the barrel extension in to the upper receiver. This holds it in position completely front to back in the upper receiver. Otherwise if there is any play (and then there typically is) it merely hangs around the face from the upper receiver completely determined by the facial area from the upper receiver since the sole source of support for 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 want a gas block that does not impose pointed stress in the barrel. Clamp-on types that grab all the way up throughout the barrel are great. The blocks which are pinned on with tapered pins that wedge against the barrel or the slip on kind of block with set screws that push up from underneath (or entirely on the barrel) can deform the bore within the barrel and will wreck the accuracy of your otherwise great barrel.
6. Free-Float Handguard: A rigid, free-float handguard (and so i emphasize the saying rigid) really makes a difference. There are many types of free-float handguards plus a free-float handguard is, in and also itself, a massive improvement more than a non-free-float put in place, but best can be 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 almost any rest, bipod, front bag, etc., a rigid fore-end is best since ARs would like to jump, bounce and twist if you let an attempt go, since the carrier starts to begin its cycle just before the bullet exits the bore.
7. Barrel Contour: You need some meat around the barrel. Involving the upper receiver and also the gas block don’t go real thin by using a barrel (we love to 1? diameter if it’s workable weight-wise). Once you touch off a round and also the bullet passes the gas port, the gas system immediately starts pressuring track of a gas impulse that gives vibrations and stress on the barrel, especially between the gas block to the receiver. A heavier barrel here dampens that. Staying a little bit heavier with barrel contour from the gas block area and to the muzzle is perfect for exactly the same reasons. ARs have a lot happening when you touch off a round and the gas system pressures up and also the carrier starts moving (all just before the bullet exits the bore) so 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 want a gas tube that runs freely through the barrel nut, throughout the front of the upper receiver, and thru the gas key within the carrier. Guarantee the gas tube is not really impinged by any one of them, so it does not load the carrier in the 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 to the barrel than would normally occur. We sometimes spend a 63dexjpky of time moving the gas block with gas tube on / 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 need to avoid over-porting the gas port. Being over-gassed helps make the gas system pressure up earlier and a lot more aggressively. This leads to more impulse, and increases forces and vibration affecting the very best end along with the barrel. Tune the gas port to give the amount of pressure needed to function properly and adequately but no more.
10. Front/Back Bolt Play: If accuracy is the game, don’t leave a lot of front/back bolt play (keep it .003? but a maximum of .005?). We’ve seen factory rifles run .012? to .015? play, which can be OK if you have to leave room for grime and dirt in the military application. However, that volume of play is not really ideal for a higher-accuracy AR build. Plenty of front/back bolt play allows rounds to be hammered to the chamber and also re-formed in a non-consistent way, since they are loaded in the chamber.
11. Component Quality: Use good parts from the reputable source and become wary of “gun show specials”. All the parts are NOT a similar. Some are great, some are not so excellent, and a few aftermarket parts are simply bad. Don’t be afraid to utilize mil-spec-type carriers; by and large they may be excellent for an accuracy build. Also, do not forget that just because a carrier says “National Match” or something that is else into it does not always mean it’s any better. Be skeptical of chrome-plated parts as being the chrome plating can transform the parts dimensionally and might also help it become difficult to do hand-fitting for fit and function.
12. Upper to lessen Fit: A great upper/lower fit is effective. For quick and dirty fit enhancement, an Accu-Wedge from the rear helps a great deal. The best option would be to sleep the top to your specific lower so that the lower and upper, when together, are definitely more like one integral unit. To the upper receivers we produce, we attempt to find the specs as close since we can, but still fit the numerous lowers on the market place.
13. Muzzle Attachments: Don’t screw within the muzzle (literally). Leave just as much metal on the barrel in the muzzle that you can. People like to thread the muzzle for any flash hider, suppressor, muzzle brake, or some other attachment, but if you really want accuracy, leave the maximum amount of metal that you can there. And, in case you have something which screws on, set it up up so that it can be put on and possess it stay there without putting plenty of torque and stress into it right the location where the bullet exits the bore. If you are going to thread the end in the barrel, help it become concentric with the bore and make certain whatever you screw on there is just as well. For all those muzzle attachments, also ensure that the holes through which the bullet passes through are dead true to the bore. Many aftermarket screw-on everything is not good that way. Everything that vents gas should vent symmetrically (i.e. whether it vents left, it must vent equally right, and likewise, if it vents up, it must vent down equally). Uneven venting of gas can wreck accuracy.
14. Quality Ammunition: Ammo can be a whole story on its own, but loads that happen to be too hot typically shoot poorly in best AR15 manufacturers. If you need 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 basically had exactly the same features and things completed to them as explained in this article, plus they all shot great.