March 19th, 2022

Saturday at The Movies: AR Platform Set-Up & Maintenance

Brownells tech tip video AR15 ar platform rifle gunsmithing

Do you own or shoot an AR-platform “black rifle”? Then you know these rifles run dirty, and have some unusual maintenance requirements. On the other hand, the AR “Modern Sporting Rifle” is fun and versatile with a vast range of options among buttstocks, barrels, handguards, and grips. You can assemble a simple 16″ barrel .223 Rem rig for home defense, or build a long-barreled 6mm ARC rifle with bag-rider buttstock and high-magnification optic for long range target work. The choice is up to you.

To help with your black rifle journey, here are eight helpful videos from Brownells. These will help ensure your AR rifle cycles reliably and runs longer, with reduced wear. Brownells also explains how to choose the optimal barrel twist rate. CLICK HERE to order AR parts, accessories, and ammo from Brownells.

AR Bolt/Bolt Carrier Lubrication — Smarter Methods

This video shows the proper way to lubricate an AR-15 bolt-carrier assembly. The video identifies the key metal-on-metal friction points where you actually need lubrication: the rails on the underside of the carrier, shiny wear points on top, and just a dab on the cam pin. How much oil/lubricant should you use? The AR-15 is pretty forgiving on that point. Some spots work best with grease, others work best with a lighter oil. Just keep it out of the combustion areas. Those little holes in the carrier are gas vent holes, NOT oil holes!

AR Maintenance — General Cleaning Procedures

Let’s face it, ARs with the original gas system tend to run dirty. You’ll need to regularly clean the bolt carrier and bolt. In addition you should regularly clean the chamber area and the inside of the upper. Also make sure to clean the lower (see video 3:15) and ensure the trigger assembly is properly maintained. This video covers general cleaning and maintenance of AR-platform rifles. We highly recommend that all new AR owners watch this video. NOTE: When cleaning the bolt, don’t forget the extractor recess and ejector recess. The majority of ARs we’ve seen that did not function properly had gunk (lube, carbon, brass shavings) clogging these areas.

AR Barrel Twist Rates — What You Need to Know

AR barrels can be ordered with a variety of twist rates from 1:12″ to 1:7″. Basically, the longer/heavier the bullet you plan to shoot, the faster the twist rate you need. For example, Sierra recommends a 1:7″ twist rate for the 90gr SMK. A 1:12″ could work with the small lightweight bullets up to 55 grains. The 1:9″ barrel will stabilize the light and mid-weight bullets up to about 77 grains. We recommend a 1:8″ or 1:7″ twist rate for the best versatility. You’ll find a detailed discussion of AR twist rates on PewPewTactical.com.

How to Install an AR15 Trigger Assembly

One of the most common AR upgrades done by black rifle owners is swapping out the trigger for a better unit (perhaps a two-stage). Trigger replacements on ARs can be done fairly easily with basic tools. But there are some recommended procedures to ensure the trigger group swap goes easily. You’ll want to have a proper mount to secure the lower, and tools that fit the pin diameters on your lower.

Must-Have Spare Parts for AR-Platform Rifle

With 350,000 views, this is one of the most-watched AR videos on the Brownells YouTube Channel. Brownells Gun Techs Steve and Caleb list key spare parts AR owners should have. Top of the list are bolt gas rings, which wear out through normal use. Also you’ll want a spare extractor spring and pin, because these both can fail. The cotter pin and cam pin can break, but more often they get lost when the Bolt Carrier Group is disassembled for cleaning. Additionally, the large buffer springs wear out with time, so have a spare. Downstairs on the lower receiver, keep spare springs and detents for the pivot and takedown pins. Finally, if you’ve upgraded your trigger, keep the original one as a backup spare.

Checking Headspace on ARs

In this Tech Tip, Brownells gun tech Steve Ostrem walks users step-by-step through the process of checking headspace on their AR-15 rifles, both new and used. It is very important to have proper headspace to ensure proper feeding and extraction, and to ensure good brass longevity (with less risk of dangerous case separation). Starting at 2:10, this video explains how to check headspace with go/no-go gauges and maximum headspace gauge. Ostrem notes: “If you have an AR that closes on a no-go gauge, we recommend taking it to a gunsmith before heading to the range.”

brownells AR AR15 headspace video go gauge
Excessive headspace in AR platform rifles can lead to dangerous case separation.

Setting Up Gas Tube Systems

This Tech Tip examines AR-platform gas systems, and shows how to select the proper length gas tube, and how to configure multiple tube systems if you change your barrel to different lengths. This is worth watching for anyone re-barreling an AR.

Barrel Gas Block Alignment — Key to Reliable Cycling

In this video, Brownells gun tech Steve Ostrem explains surefire methods to align your gas block. The most common problem with AR builds is poor cycling, commonly caused by misalignment between the gas block and the barrel’s gas port.

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