January 24th, 2017

GUN TECH — How to Build a Truly Accurate AR-Platform Rifle

AR-X AR15 Upper

A lot of claims are made about accuracy for AR-platform rifles, but much of that is just “sales talk”. But if you want a truly accurate black rifle, there are some key upgrades that, collectively, can transform a plain jane AR into a true tack-driver. Here’s an article by a genuine AR expert that will help you identify those components that really make a difference — the parts that can deliver true “match-grade” accuracy. Built right, a modern AR can deliver half-MOA accuracy with handloads. In this article, Robert Whitley explains how that’s done.

In our Shooters’ Forum, one member recently asked: “What makes an AR accurate? What parts on an AR can really affect accuracy — such as free-floating handguards, barrels, bolts, bolt carriers?” Robert Whitley posted a very comprehensive answer to this question, based on his experience building and testing dozens of AR-platform rifles. Robert runs AR-X Enterprises, which produces match-grade uppers for High Power competitors, tactical shooters, and varminters.

AR-X AR15 Upper

Building an Accurate AR — What is Most Important

by Robert Whitley
There are a lot of things that can be done to an AR to enhance consistent accuracy, and I use the words “consistent accuracy” because consistency is a part of it (i.e. plenty of guns will give a couple great 5-shot groups, but won’t do a very good 10- or 20-shot groups, and some guns will shoot great one day and not so good on others).

Here are 14 key things we think are important to accuracy.

1. Great Barrel: You’ll want a premium match-grade barrel, well-machined with a good crown and a match-type chambering, true to the bore and well cut. The extension threads must also be cut true to the bore, with everything true and in proper alignment.

2. Rigid Upper: A rigid, heavy-walled upper receiver aids accuracy. The typical AR upper receiver was made for a lightweight carry rifle and they stripped all the metal they could off it to make it light to carry (which is advantageous for the military). The net result are upper receivers that are so thin you can flex them with your bare hands. These flexible uppers are “strong enough” for general use, but they are not ideal for accuracy. Accuracy improves with a more rigid upper receiver.

3. True Receiver Face: We’ve found that truing the receiver face is valuable. Some may argue this point but it is always best to keep everything related to the barrel and the bore in complete alignment with the bore (i.e. barrel extension, bolt, upper receiver, carrier, etc.).

4. Barrel Extension: You should Loctite or glue the barrel extension into the upper receiver. This holds it in place all the way front to back in the upper receiver. Otherwise if there is any play (and there typically is) it just hangs on the face of the upper receiver completely dependent on the face of the upper receiver as the sole source of support for the barrel as opposed to being made more an integral part of the upper receiver by being glued-in.

AR-X AR15 Upper5. Gas Block: You want a gas block that does not impose pointed stress on the barrel. Clamp-on types that grab all the way around the barrel are excellent. The blocks that are pinned on with tapered pins that wedge against the barrel or the slip on type of block with set screws that push up from underneath (or directly on the barrel) can deform the bore inside of the barrel and can wreck the accuracy of an otherwise great barrel.

6. Free-Float Handguard: A rigid, free-float handguard (and I emphasize the word rigid) really makes a difference. There are many types of free-float handguards and a free-float handguard is, in and of itself, a huge improvement over a non-free-float set up, but best is a rigid set-up. Some of the ones on the market are small diameter, thin and/or flexible and if you are shooting off any type of rest, bipod, front bag, etc., a rigid fore-end is best since ARs want to jump, bounce and twist when you let a shot go, as the carrier starts to begin its cycle before the bullet exits the bore.

7. Barrel Contour: You want some meat on the barrel. Between the upper receiver and the gas block don’t go real thin with 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 up with a gas impulse that provides vibrations and stress on the barrel, especially between the gas block back to the receiver. A heavier barrel here dampens that. Staying a little heavier with barrel contour through the gas block area and out to the muzzle is good for the same reasons. ARs have a lot going on when you touch off a round and the gas system pressures up and the carrier starts moving (all before the bullet exits the bore) so the more things are 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, through the front of the upper receiver, and through the gas key in the carrier. Ensure the gas tube is not impinged by any of them, so that it does not load the carrier in a stressed orientation. You don’t want the gas tube bound up so that when the gas tube pressures up it immediately wants to transmit more force and impulse to the barrel than would normally occur. We sometimes spend a lot 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 get them right — factory tubes may work OK but they typically do not 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 more aggressively. This causes more impulse, and increases forces and vibration affecting the top end and 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 no more than .005″). We’ve seen factory rifles run .012″ to .015″ play, which is OK if you need to leave room for dirt and grime in a military application. However, that amount of play is not ideal for a high-accuracy AR build. A lot of front/back bolt play allows rounds to be hammered into the chamber and actually re-formed in a non-consistent way, as they are loaded into the chamber.

11. Component Quality: Use good parts from a reputable source and be wary of “gun show specials”. All parts are NOT the same. Some are good, some are not so good, and some aftermarket parts are simply bad. Don’t be afraid to use mil-spec-type carriers; by and large they are excellent for an accuracy build. Also, remember that just because a carrier says “National Match” or something else on it does not necessarily mean it’s any better. Be wary of chrome-plated parts as the chrome plating can change the parts dimensionally and can also make it hard to do hand-fitting for fit and function.

AR-X AR15 Upper

12. Upper to Lower Fit: A good upper/lower fit is helpful. For quick and dirty fit enhancement, an Accu-Wedge in the rear helps a lot. The ultimate solution is to bed the upper to a specific lower so that the upper and lower, when together, are more like one integral unit. For the upper receivers we produce, we try to get the specs as close as we can, but still fit the various lowers in the market place.

13. Muzzle Attachments: Don’t screw up the muzzle (literally). Leave as much metal on the barrel at the muzzle as you can. People like to thread the muzzle for a flash hider, suppressor, muzzle brake, or some other attachment, but if you really want accuracy, leave as much metal as you can there. And, if you have something that screws on, set it up so that it can be put on and have it stay there without putting a lot of torque and stress on it right where the bullet exits the bore. If you are going to thread the end of the barrel, make it concentric with the bore and make sure what you screw on there is as well. For all muzzle attachments, also ensure that the holes through which the bullet passes through are dead true to the bore. Many aftermarket screw-on things are not so good that way. Anything that vents gas should vent symmetrically (i.e. if it vents left, it should 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 a whole story by itself, but loads that are too hot typically shoot poorly in an AR-15. If you want accuracy out of an AR-15, avoid overly hot loads. Shown below are test groups shot with four (4) different uppers, all with moderate loads. These four uppers all pretty much had the same features and things done to them as explained in this article, and they all shot great.

AR-X AR15 Upper

Robert Whitley
www.6mmAR.com

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January 24th, 2017

Shooting Skills: Reading the Wind When Hunting

Norway Hunting Snow

Thomas Haugland, a Shooters’ Forum member from Norway, is a long-range target shooter and hunter. He has created an interesting video showing how to gauge wind velocities by watching trees, grass, and other natural vegetation. The video commentary is in English, but the units of wind speed (and distance) are metric. Haugland explains: “This is not a full tutorial, but rather a short heads-up to make you draw the lines between the dots yourself”. Here are some conversions that will help when watching the video:

.5 m/s = 1.1 mph | 1 m/s = 2.2 mph | 2 m/s = 4.5 mph
3 m/s = 6.7 mph | 4 m/s = 8.9 mph | 5 m/s =11.2 mph

More Interesting Videos from Norway
There are many other interesting videos on Haugland’s YouTube Channel, including Game Stalking, Precision Reloading, and Tips on how to use a Mildot Reticle on a scope with MOA-based clicks.

Permalink - Videos, Hunting/Varminting, Shooting Skills 4 Comments »
January 24th, 2017

Atty. Gen’l Nominee Expresses Strong 2d Amendment Support

Republican Attorney General nominee U.S. Senator Jeff Sessions Alabama Trump administration
Sen. Jeff Sessions photo by Gage Skidmore, Wikipedia, CC-BY-SA-3.0 attribution.

U.S. Senator Jeff Sessions (R-Alabama) took a firm position on Second Amendment rights during Congressional hearings on his nomination to be the next Attorney General of the United States. Sessions testified before the Senate Judiciary Committee on a wide range of topics. The former Attorney General for Alabama and U.S. Attorney for the Southern District of Alabama was clear that the Second Amendment would be respected as an individual right by the Trump administration.

“Well, I do believe the Second Amendment is a personal right,” Sessions said in response to questions. “It’s an historic right of the American people, and the Constitution protects that and explicitly states that. It’s just as much a part of the Constitution as any of the other great rights and liberties that we value. So my record is pretty clear on that.”

The National Shooting Sports Foundation urged Sessions’ confirmation based on his commitment to gun ownership rights and his strong track record as a U.S. Attorney. NSSF Senior VP and general counsel Lawrence Keane stated: “Through numerous attacks on our Second Amendment liberties, Senator Sessions has worked tirelessly to protect the rights of law-abiding citizens, including through his staunch support of the Protection of Lawful Commerce in Arms Act. We are confident that with Senator Sessions as the top law enforcement officer in the nation that our public will be safer, that criminals will be taken off the streets, that justice will be served, law enforcement priorities will take precedence over politics and the Second Amendment rights of law-abiding Americans will be respected.”

Sessions vowed to the Senate committee that scapegoating the firearms industry and lawful gun owners for the use of guns in crimes committed by individuals would come to an end: “The first and foremost goal I think of law enforcement would be to identify persons who are dangerous, who have a tendency or have been proven to be law breakers and been convicted and those who are caught carrying guns during the commission of a crime,” he explained.

“If I am confirmed, we will systematically prosecute criminals who use guns in committing crimes,” Sessions added. “As United States attorney, my office was a national leader in gun prosecutions nearly every year. We were partners with state and local law enforcement to take down these major drug trafficking cartels and dismantle criminal gangs.”

Biography of Sen. Jeff Sessions
Jess Sessions received a J.D. degree from the University of Alabama in 1973. Sessions served in the U.S. Army Reserve from 1973 to 1986, attaining the rank of Captain.

Sessions has had a distinguished legal career, first as a practicing attorney in Russellville, Alabama, and then in Mobile. Following a two-year stint as Assistant United States Attorney for the Southern District of Alabama (1975-1977), Sessions was nominated by President Reagan in 1981 and confirmed by the Senate to serve as the United States Attorney for Alabama’s Southern District, a position he held for 12 years. Sessions was elected Alabama Attorney General in 1995, serving as the state’s chief legal officer until 1997, when he entered the United States Senate.

As a United States Senator, Sessions has focused his energies on maintaining a strong military, upholding the rule of law, limiting the role of government, and providing tax relief to stimulate economic growth.

This article based on report in Midsouth Shooters Supply Blog by Glen Zediker.

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