[How-To Guide]: Accurizing the AR-15

Semi-automatics were once considered to be inaccurate rifles.

For the longest time, bolt rifles were the king of accuracy.

The truth is, a properly built semi-automatic rifle, like the AR-15 or LR-308, using quality components with match grade ammo can be excellent at precision at extended ranges.

I will be going over some quality components to look at for your next build, assembly techniques, and some DIY techniques to squeeze the accuracy out of your AR.

The Barrel

Possibly the most important aspect of your rifle is the barrel.

Beyond rifle twist, barrel length, and contour, the thing that shooters don’t take into consideration is the barrel concentricity and how well the rifling is cut.

People tend to buy with their wallets instead of what the rifle will be used for.

If you're going for precision, a bargain barrel is a gamble at best when you are shooting for sub-MOA accuracy. This is not where you want to skimp with a new build.

For the sake of building, there are plenty of options that can be a great choice depending on your budget. A proper barrel is the best way to enhance the mechanical accuracy of a weapon.

Do ample research, read reviews, and choose a company with a proven track record.

Some of my personal favorite barrels are made by Ballistic Advantage. For their price point, they tend to be highly accurate barrels, and they tend to be more affordable when buying for 5.56 NATO/.223 Wylde, or even .308 Winchester and 6.5 Creedmoor.

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If money is no object, Proof Research makes barrels that are superbly consistent and go through much more strenuous quality control measures.

But that comes with a price. Barrels can cost as much as some people’s budget AR-15 builds as they are north of $400. Proven and verifiable accuracy standards do not come cheap.

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Check out some more of our favorites in Best AR-15 Barrels.

Installation Matters

Even if you buy the best barrel that money can buy, it doesn’t necessarily mean that it will shoot if you don’t abide by some certain aspects of assembly.

I am a stickler for proper assembly. It matters and if you are building a precision AR it matters even more.

Proper tools are something that any serious builder needs.

With the right budget, you can get all sorts of tools for the trade, but the bare minimum needs to be a proper torque wrench to properly torque the barrel nut to mate the barrel to the upper receiver.

One of our favorite overall kits is the Real Avid. Check out our full review here.

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Always verify the proper torque value with whatever manufacturer’s barrel nut that you use.

Speaking of barrel nuts, free-floating your barrel is important in reducing group sizes for precision.

The AR industry has shifted to free-floated handguards and for good reason. Don’t get me wrong, an M4orgery can be plenty accurate.

Check out some of our favorite handguards here.

Yearly, I cleaned up shop at 500 yards while serving in the Marine Corps.

But if you expect sub-MOA groups, you must ditch the plastic handguards and get with the times.

Free-floating a barrel nut and proper torque isn’t enough though.

Proper mating of the barrel extension to the upper receiver needs to be considered as well.

It should be a tight fit.

And when I mean tight, I mean tight.

If you look up the reviews or talk to people with experience, most would agree that Bravo Company USA has some of the tightest upper receivers you can buy.

So tight that for installation sometimes heat and cold are needed to properly join a barrel and upper receiver in holy matrimony.

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The tighter the joining the more rigid and anchored the barrel is to the upper receiver and how it integrates with the bolt lock-up. Consistency is king.

Get some proper Aeroshell 33MS Grease on the threads. And I like to install/uninstall the barrel nut 2-3 times before the final time.

Speaking of consistency, a properly trued upper receiver face so that the barrel extension shoulder uniformly mates to the upper is also important. 

If you are looking for something out of the ordinary, I would highly recommend Eisenach Arms with their left side-charging, right side ejecting upper receiver.

I have one and the precision of quality, fit, and finish would be an excellent choice for a long-range precision AR-15. It is a billet upper and the anodizing is fantastic.

They come from the factory with the face of the upper trued for ultimate precision.

But Can You Polish a Turd?

Don’t get me wrong. I have bought and built with plenty of budget-minded parts for the AR.

Some of which have been great for the price, but you do still get some loose spec items.

Is there anything that you can do as a project to increase the precision and consistency of your AR? Or maybe help tighten up groups with your next build?

You can! But like most things in the world, it's going to cost you money, some research, and patience.

The topics covered below should not be done by someone that is mechanically illiterate, and if you have any doubt in your abilities, STOP. Get a competent gunsmith to do the work.

One thing that you can do is to ensure a tight fit with your barrel and upper receiver.

If the upper receiver and barrel have some wiggle room, you can tighten it up and provide better consistency by using a bedding material like Loctite 620.

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I am NOT talking about putting Loctite on your upper receiver threads.

This is applied to your barrel extension and when pressed into the upper, the compound beds the barrel for a tighter and more uniform fit once it dries.

Some people have even shimmed the barrel with a thin piece of aluminum, but honestly, if it requires a shim to get a tight fit, its worth using a warranty or scrapping the out of spec upper receiver.

Another option that you can do to possibly increase precision is lapping the face of your upper receiver.

All that is required is a lapping tool and lapping compound that marginally and incrementally trues the face of your upper receiver by wet sanding.

I own a Brownells' Upper Receiver Lapping tool and they also offer lapping compounds in varying grit.

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With the tool chucked into an electric drill, and while keeping the upper receiver vertical and in a stable position with a vise, you can properly true the face of the upper within a few minutes.

If you take it slow and check your results often, it is an easy task. Once the outer ring on the face of the upper is shiny and anodizing is stripped the whole way around, you have faced your upper.

Mechanical Accuracy vs. Practical Accuracy

Above, I covered topics to potentially increase the mechanical accuracy of the firearm.

There is an important distinction between mechanical accuracy and practical accuracy, a.k.a. “shooter accuracy.”

It's important because even if a rifle can “circumcise a fly at 300 yards”, it doesn’t mean it will behind any type of shooter.

Beyond the skills needed to properly shoot with precision, like trigger control, proper aiming, and breathing control, you can help the situation by making it easier and more repeatable.

The best way to help practical accuracy is training and trigger time. But getting a silky, butter-smooth trigger is also a great idea.

Geissele is the gold standard. One of the best triggers in their lineup is the Highspeed National Match trigger. It is slightly modular.

This trigger comes with 3 spring sets to customize the pull weight for your given task, whether you are shooting CMP competitions, tactical shooting, or a light crisp pull with their match set.

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There are many other triggers for different roles with Geissele. You get what you pay for.

One of my favorite drop-in cassette-style triggers is the Timney AR-15 Competition trigger.

The pull weight is a consistent 4lbs. and the components inside of the cassette is of the highest-grade steel that is EDM machined, precision ground, and properly heat treated.

It is currently sitting in my 6.5 Creedmoor.

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Check out more of our favorite AR-15/AR-10 Triggers.

Parting Shots

As stated before, if you do not feel comfortable with some of the methods of accurizing the AR, get a competent gunsmith to perform the tasks you want. Every person’s skill set is different.

Also, nothing can compete with quality trigger time if you want to get better at shooting and be more precise. The ABCs of marksmanship still need to be followed to maximize the mechanical accuracy of a rifle!

Finally, accuracy is also highly dependent on ammo! If you want match-grade performance, you must buy match grade components or factory loaded ammo.

With companies like Barnes, Federal Premium, and Hornady there are plenty to choose from.

Have you done some DIY accurizing on your AR? Have you noticed a difference by lapping the upper receiver or bedding your AR barrel? Let us know in the comments below! Find the best AR-15 upgrades to keep your newly accurized toy hitting the mark.