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June 22nd, 2021

AR Platform Video Series from Brownells — Watch and Learn

Brownelss 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 four 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 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.

Barrel Gas Block Alignment — Key to Reliable Cycling

In this Tech Tip, 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.

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.

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November 29th, 2015

Cortina’s Corner: Rebarreling an AR15 to 6.5 Grendel

Erik Cortina barrel 6.5 Grendel

Here’s an interesting project — using a second-hand barrel to upgrade an AR15. Our friend Erik Cortina decided to make his AR15, originally chambered in 6.8 SPC, into a 6.5 Grendel. Erik acquired a “pre-owned” 6.5-06 match barrel through our Shooters’ Forum. Erik inspected the barrel with a bore-scope and confirmed it was in good shape after the first few inches (past the chamber). The 6.5-06 barrel had more than enough length, so he trimmed off the chamber end, then contoured the barrel to fit his AR15. This is a smart way to upgrade a gun without spending $350 or more on a brand new barrel.

In the first video, Erik explains the process of converting his 6.8 SPC AR15 into a 6.5 Grendel: “I take the upper completely apart and pull barrel off which will be used to take dimensions for new barrel. The new barrel will be turned from an old competition heavy barrel. All the barrel reaming will be done using JGS reamers. I will also use JGS reamers to make a seating and F/L sizing die.”

In the second video, Erik contours the “pre-owned” barrel to fit his AR. He uses an old bolt-action 6.5-06 competition barrel and cuts it to 17″ long and contours it to fit his AR-15. The barrel is turned down on a manual lathe to .750″ outside diameter for the majority of its length in order to fit the gas system barrel block that is made for a .750″ barrel. After contouring, the barrel will be threaded and chambered.

6.5 Grendel AccurateShooter.com cartridge Erik Cortina

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