Gun Care

AR Building and Gunsmithing — Tools of the Trade

Tool for gunsmithing and working on AR15s

The modern sporting rifles that range from the AR-15s and AR-10s, pistol-caliber carbines, and the AK-47 and AK-74 formats are fun to work on for the home builder. Usually though, the DIY builder can create a much higher quality firearm if they use right ‘tools of the trade’ to do the job. Despite the DIYers’ best efforts, standard garage tools usually are not well suited for gunsmithing work on firearms requiring specialized tools.

Gunsmithing Tools

Most of us have first-hand experience with the problems of using the wrong tools to build firearms. The result is parts that easily loosen, are visibly damaged, or an errant strike that makes an otherwise professional-quality build look homemade. Beyond castle nuts and barrel nuts, which are easily damaged without specialized tools to properly tighten and torque these nuts, there are many other gunsmithing tools that make firearm builds more reliable and scratch and mar-free. Even a set of quality hex and torque wrenches can make the difference between stripped screw heads on a handguard and an attractive build with property torqued screws.

MWI AR Receiver block with an AR15 lower receiver
The MWI AR Receiver block was used to build this PWS-based lower.

For the DIY builder, some type of bench or vice block, quality punches, and an AR wrench are a big first step to preventing damage during assembly or upgrades. Bench and vice blocks come in many forms. A high percentage of accidental DIY damage occurs due to either unretained or improperly retained receivers during the assembly process. Inevitably many of the assembly processes require a third hand and doing without reliable and rugged receiver retention usually ends up with the receiver bouncing — at least once — off the table or out of a lap.

The above receiver block and rod alternatives greatly assist the DIY builder to assure parts do not start bouncing around the room. Securing the receivers is also especially handy when driving roll pins and torquing barrel and castle nuts. Even handguards, gas blocks, and muzzle devices usually all benefit from a securely retained receiver.

The Geissele Action Rods are specifically designed for barrel installation and torquing, however, they are extremely useful in the general assembly of the uppers. Other products such as the Midwest Industries Receiver Blocks offer DIYers broad use blocks that can be used for everything from upper and lower assembly, gas block installation, and receiver pin installation. MWI noted these provide that critical third hand that you always need during the assembly process.

Midwest Industries also created similar receiver blocks for the DPMS AR-10 format, AK-47/74 formats and Glock magazine PCC or pistols which are worth their weight in gold for the home builder. Even if a builder is simply performing a full assembly cleaning or upgrading simple parts, these receiver blocks are critical to assuring those processes are damage-free. An especially useful feature of the MWI block is the simple but extraordinarily handy built-in parts trays which provide a place for the parts without them rolling all around the bench. There are many different receiver blocks on the market, but not many manufacturers offer such a wide array of firearm blocks as MWI, which includes the full AR, AK, and Glock format firearm blocks for $40 MSRP.

MWI – Midwest Industries AR-15 Receiver Block

  • Designed to work with Mil-Spec AR-15 forged lowers
  • High-strength polymer construction
  • Allows for gas block roll pin installation
  • Mounting holes for attachment to bench or alternative work surface
  • Parallel edges for vice use
  • Trigger guard installation section
  • Allows lower to be held for multiple aspects of assembly
  • Fire control pin assembly
  • Able to hold complete firearm for maintenance
  • Small parts tray
  • Weight: 12.0 oz
  • Height: 6.5”
  • Length: 5.0”
  • Width: 1.25”
  • Made in the USA
AR15 Barrel and Assembly tools
AR-15 Barrel and Upper assembly tools like this Geissele and PRI deliver rock-solid barrel torque mounting of uppers.

Specialized Upgrades

Upgrading the home builder kit with a Magpul AR wrench, Wheeler Fat Wrench, quality punches, and a brass gunsmith hammer drastically improve build quality for the home builder. The Magpul Armorer’s Wrench features the common closed-ended wrench sizes for AR builders plus a proper castle nut and barrel nut wrench that prevents common castle- and barrel nut damage home builders too often deliver in their builds. I have personally been using a Magpul Armorer’s Wrench since it was introduced, and it has performed exceptionally — even during the more difficult barrel nut removal rebuilds.

Quality punches such as Wheeler, Grace, and Bostitch really do make a difference during assembly even though they are consumable items like hex and torx wrenches that lose tolerances through use. Small 4-ounce brass and other non-marring hammers from Grace are of exceptional quality and prevent the inevitable hammer slip that will happen during assembly. Even though specialized nail setting and center punches are inexpensive, they can prove to be some of the most useful for starting, driving, and final recessing of roll pins without the typical challenges of flat head punches slipping off the roll pin head.

Other consumables such as standard isopropyl alcohol in a spray bottle, WD40, red and blue Loctite, high-temp copper anti-seize, and Loctite 638 all elevate a build from homemade to professional. For cleaning, there is nothing as safe and easy to use as standard drugstore 40% isopropyl rubbing alcohol in a plastic spray bottle, which cleans off grease and grime well and evaporates quick — it is also useful for prepping parts for Loctite and anti-seize as well as cleaning.

Bostitch, Wheeler, Real Avid and Grace punches
A quality set of punches from Bostitch, Wheeler, Real Avid, or Grace are required, but consumable shot tools and a small brass hammer deliver a non-maring driver

WD-40 is, of course, the go-to CLP — Cleaner Lubricate and Protectant used by… well everyone and remains a standard all-purpose CLP. High Temp Copper Anti-seize is used exclusively for barrel threads to allow proper torque while preventing thread seizing between the steel and aluminum. Loctite blue (removable) or red (permanent) are perfect for those parts which need help staying put; most pro builders use red Loctite on the castle nut and muzzle devices.

Just a little heat from a torch with any Loctite will allow it to be removed with reduced effort. Loctite 638 is a specialized gap filler compound that is essentially a liquid shim. Some of the highest tier of AR builders use Loctite 638 on the upper receiver and barrel surfaces to assure when the barrel is installed it will have the most secure and tight mated surfaces possible to maximize accuracy.

Wheeler FAT Wrench
The Wheeler Fat Wrench is indispensable to assure perfect assembly torque without stripping screws.

Final Thoughts

Though it is certainly possible to assemble and work on modern sporting rifles and firearms with basic garage tools, we all know that to have a quality professional build with proper torque and without dings and scratches, the right gunsmithing tools and consumables are required. Even if you are a seasoned builder, it is worth looking at some of these tools to upgrade the quality of your next build.

Have you ever built your own gun or done any DIY gunsmithing? What tools did you use? Did your experience lead to a tip you can share with others? Share your answers in the comment section.

  • two sets of Allen wrenches
  • AR15 Barrel and Assembly tools
  • Tool for gunsmithing and working on AR15s
  • Wheeler FAT Wrench
  • Universal blocks from Midwest Industries to hold guns in a vice
  • MWI AR Receiver block with an AR15 lower receiver
  • Bostitch, Wheeler, Real Avid and Grace punches
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (2)

  1. Good morning,
    A suggestion: compile a comprehensive, recommended tool package sorted by format, maybe with check boxes for inclusion or exclusion on an order. Would make it pretty easy to for lazy/busy folks. I suck at piecemealing things together (time) and packaged kits provide organization and efficiency. Bonus – soft case or cordura-like roll up organizer with a couple of grommets to hang in case we’re not at our home bench.

  2. Roll pin installation punches (The ones with a hole in the end) Make it very easy to start the pins. Then use a roll pin punch with a dimple on the end to drive them home.

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