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The Best Tools To Build And Maintain The AR-15

So you are building an AR, great! Welcome to the adult Lego club. Now you’re looking for the best tools to build and maintain the AR-15. Building AR’s is a lot of fun, and not nearly as daunting as it may seem, especially with the right tools. Trust me when I say is much more enjoyable and much, much less frustrating when you use the proper tools. Those same tools should also be a reputable brand and of high quality, remember the old adage, ” buy once, cry once”. So join me on our little stroll through armorer’s paradise as I list out the best tools for the job.

Midwest Industries Professional Armorer’s Wrench

A good armorer’s wrench is absolutely essential for any tool kit or box. A good wrench will help you install and remove barrel nuts, castle nuts, muzzle devices and much more. The one from MI is great quality and packed with features. Here’s a few facts from the website:

  • Designed to work with 5.56 and 7.62 AR platform rifles components
  • Works with encapsulated and pin style barrel nuts including the GI style nut
  • Drive end for all MI free float barrel nuts – Including CRM,SLH,CRT,CRLW,ULW,G3M,G4M,SP Series
  • ¾ inch wrench for A2 muzzle devices and designed to work with the thin flats on many of the popular suppressor mounts
  • Castle nut driver with 3 notch engagement
  • Combat bottle opener
  • Small hammer head
  • Torque specs features on wrench handle.
  • Constructed from 4140 heat treated steel
  • 1/2 Inch drive for torque wrench (2)
  • Made 100% in the USA

There is one thing not listed here, and that is dimensional tolerances. Tolerances are really important when fitting two things together, like a nut and a wrench. Many a time have I busted a knuckle or pissed myself off because I used a cheaper wrench that didn’t fit just right, causing it to slip off. You risk damaging your part and yourself.

This brings me to something important that is listed, its made from 4140 steel. Many of the cheap wrenches on Amazon are hit or miss with quality and you often times have no idea what they are made with. They can bend, chip or shear in the middle of you using it. Get a quality wrench and sleep easy.

PRICE: $65.99

Rock N’ Roll Pins

The AR-15 uses several roll pins in it’s assembly, so a good roll pin punch kit is vital. Trying to improperly install a roll pin will cause you to damage your firearm and look like an idiot. The Wheeler Roll Pin Install Kit is a great base to start with. It features all the roll pin starter punches and tools you will need to install and remove:

  • Bolt catch roll pins
  • Forward assist roll pins
  • trigger guards
  • Gas block/gas tube (Another option coming up soon)

The Wheeler kit isn’t bad, but there are better quality hammers and punches out there. As a starter kit or for the casual gunsmith, its a solid kit for a good price.

PRICE: $35.99

Pivot Pin Tool

The most common mishap when putting together a lower is launching a detent into the void, only to be found again with a vacuum 6 months later. Pivot and takedown detents are pretty small and under spring pressure during install, which is a recipe for disaster. Thankfully someone way smarter than me came up with an affordable easy solution, The Real Avid Pivot Pin Installation Tool. This cheap little thing makes it an absolute breeze to install your pivot pin and takes the frustration right out of it.

PRICE: $11.99

Get a Grip

Installing a grip screw can be aggravating. You can’t really see what you’re doing and the screw always seems to fall off. Many grip screws now use a hex wrench or key, this makes install and removal a little easier. Even easier if you use the Klein Tools 3/16-Inch Hex Key.

This comfortable T handle hex key is perfect for installing grip screws! As long as they are the proper 3/36 drive size. Of course it never hurts to buy a set of these just to have the other sizes available as well.

PRICE: $6.99 approximately

Other grip screws may use a slotted screw or like the MagPul grip screw, can accept both the 3/16 hex or slotted screw driver. For this reason its also good to get a good quality screw driver.

I like the Klein Tools 32303 Multi-Bit Screwdriver / Nut Driver. It’s adjustable for length and bit type so you can use it for a variety of guns or situations. Plus instead of buying a whole other screwdriver, you can just buy the bits you need instead.

PRICE: $19.99

The Rabbit Hole

If you really want to go down the AR-15 gunsmith rabbit hole, check out this list by Chad Albrecht of School of The American Rifle. SOTAR is one of the premier providers of dedicated AR-15 armorer’s courses and Chad is a wealth of knowledge.



My Students often ask for suggestions about what AR Tools, Gauges, and Jigs they should buy.

When I am asked this question its quite difficult for me to narrow down or compartmentalize a list due to the vast collection I have amassed. I promise my reluctance is not because I don’t want to help, it’s just a difficult task.

I try to buy every AR Tool, Gauge, and Jig available on the Civilian Market. I also collect U.S. Government M4/M16 Tools and Gauges. USGI Gauges and Tools are somewhat rare, very expensive, and collectible. My list will include alternatives to USGI options.

If certain Tools, Jigs, or Gauges are not available on a commercial market, I make them.

I do this because having a variety allows me to select the best tools for certain jobs. My Students also get to use, hammer on, and wrench on the tools, so I get to see how well they hold up. Students can mess up a cheap tool right quick.

So here it goes. Remember, this list is geared towards the AR but many of these items can be used to service your other firearms. If I dont suggest something you own, please don’t take offense. This list is a guideline, not the The Good Book. There will be 4 levels:

1) Basic

2) Intermediate

3) Professional

4) Insane

I will add part #’s when time permits, I’ll do my best to answer any questions.


******************BASIC LIST**************************

In my opinion these are the basic items for inspection, maintainance, and minor upgrades.

-Brownells Screwdriver (Best) or Wheeler Gunsmith Screwdriver Set (Good)

The Brownells has a lifetime warranty which means if you break a bit, Brownells will replace it with no questions asked. Using Gunsmith Bits are a MUST if you don’t want to hack up you AR, or your other firearms.

-SAE & Metric Socket Set

-Inch Pound Torque Wrench

I like the Wheeler FAT Wrench (Non Digital). The best prices are usually on Amazon. It does forward and reverse torque and clicks/breaks when it reaches it’s setting. These are great for mounting Rails, Optics, and Gas Key Screws. I own 5 of these and they have held up at my Work Bench and in Classes.

-Cheap Steel & Brass 17pc Punch Set

You can get these from Amazon. The kits come with a Spring Loaded Center Punch which can be used for Castle Nut Staking, or “Field Staking” the top of the Carrier Key.

-Tape Measure

For measuring Buffer Springs.

-.080 Weed Eater Line

-4 to 8 Ounce Ball Peen Hammer

You don’t want a roofing hammer or a claw hammer. A 4 Ounce Ball Peen is my favorite.

-Harbor Freight Rubber Mallet

Great for moving stubborn parts without damaging the material or finish.

-Harbor Freight Plastic Dead Blow Hammer

Great for moving stubborn parts without damaging the material or finish.

-Small Carbon Steel Washer

For checking parts for Magnetism.

-Digital or Analog Calipers

These are for basic checking of parts and for doing a crude a Firing Pin Protrusion check. You can buy a budget models but you can’t always trust them. In my opinion, it’s better to have a Harbor Freight Caliper than nothing, but if you can afford it a good Mitutoyo will give a lifetime of reliable service.

-1.4646 Forster 5.56 GO Headspace Gauge (Brownells)

-Feeler Gauge Set

-Obsidian Arms Punch Set

-Little Crow Gunworks Bolt Catch Tool

-Brownells Magazine Catch Install Tool

-Brownells Chamber Reflector Tool

-Starrett 117c (Best) or Mayhew 5/32×4 1/2 punch (Good)

These are for staking the Castle Nut if you don’t like using a Spring Loaded Center Punch

-Pivot Pin Install Tool

You can use an Exacto Knife, Magnet, ¼” Clevis Pin & Punch, Real Avid Tool, or other specialized Tools made for this job. The Real Avid is one of the easiest to use and cost effective.

-M-Guns Gas Tube Bender

-Brownells Gas Tube Wrench/Vise

-Snap Ring Pliers

-Geissele Hammer & Trigger Install Pin

This helps install an AR FCG, but can be used to Oil or Abrasive Lap the bores in an AR Lower Receiver if they are too small.

-AR General Purpose Brush

-Iosso AR Nylon Brush Set

I don’t use bronze or stainless brushes for firearms.

-Rapid Rod (Best) or Steel USGI Sectioned Cleaning Rod (Good)

These are not for regular cleaning. They are great for cleaning in the field and for dislodging a stuck casing.

-One Piece Cleaning Rod and AR Upper Receiver Bore Guide

-Optics Cleaning Kit

-Basic Chemicals/Solvents

Aeroshell 64 (Barrel Nuts and Castle Nuts)

Rocksett or Loctite 271/272

Blue Stick Loctite (NOT the liquid type)

Cold Blue (Steel Touch-up)

Aluminum Black (Aluminum Touch-up)

Synthetic Grease (Assembly Lube)

Kroil Oil (Seized Fastners)

Steel Wool

Loctite 620 or Permatex Indian Gasket Shellac (Barrel Bedding and for Carrier/Gas Key Installs)


Bore Cleaner (I like Wipe Out Products)

Birchwood Casey Barricade (Great for external wipe downs)

******************INTERMEDIATE LIST*****************

In my opinion, this is the bare MINIMUM for building and tearing down an AR.

-A SOLID Work Bench

You can buy small Work Bench from Lowe’s, Home Depot, and Harbor Freight, but most are very light, have very light/weak frames, and thin work surfaces. Some people are forced to use their kitchen countertops due to limited space or budget. If you mount a Vise to a flimsy or unstable Work Bench it will often move when you try to torque on things, or if you try to remove things like taper pins. If you want a good Work Bench you can get a great one for $200.00 at Walmart/Sam’s Club. Their Work Benches are named Seville Classic. They have 2″ Wood tops and are heavy. I have 5 in my Shop/Classroom and they are indestructible and they have a few sizes for those with limited space.

-4″- 6″ Vise.

You should bolt your Vise to your Work Bench and avoid clamp-on arrangements. You can get by with just a Harbor Freight Vise, but it may not last.

A Vise is a must for Installing/Removing a Barrel/Rail System, Installing/Removing a Receiver Extension, or Installing/Removing a Muzzle Device. I use the 4.5″ Yost 445 Vises from Amazon for my Shop/Classroom Work Benches and the have held up great.

Yes, people can do the above without a Vise and Work Bench, but in my experience, you’re not going to properly torque things down, or do clean work without a SOLID Work Bench and Vise.

-Vise Pads

You don’t want to grab a gun part in a Vise without Vise Pads. There are many options for this, but most are not great. In my opinion the best ones are made at home. I use Trex Decking material and Leather. The alternative is 4.5″ magnetic rubber Vise Blocks from Amazon.

-½” Foot Pound Clicker Torque Wrench

A Harbor Freight model will work here but not for a lifetime of uses. Do your research and buy the best one you can afford. The beam types will work, but they are not easy to deal with when cranking on an AR. Torque Wrenches remove the human element from a job and create consistency in the work. I can build an AR without one, but I still use a Torque Wrench.

-Tapco Multi Tool Green Armorers Wrench

Yes, Tapco. My second choice is the Magpul Armorers Wrench. It’s the most versatile wrench when it comes to aftermarket parts like barrel nuts, muzzle devices, and receiver extensions. It isn’t as comfortable to use as others, but it is a great wrench with a great warranty.

-Geissele Reaction Block or Kley Zion Buffer Tube Jig

Which one you select depends on what you will be working on. The Geissele ONLY works on Milspec Receiver Extensions. The Kley Zion works on Milspec AND Commercial Receiver Extensions. So if you only own Milspec Receiver Extensions, the Geissele is best. If you will be working on other people’s AR’s , you have no control on what they will bring you and I guarantee there will be Commercial Receiver Extensions you have to contend with.

-Wood Block

Good for supporting Barrel when using a Reaction Rod type tool, and good for hammering on FSB Taper Pins.

-Magpul BEV Block

The BEV Block does work as a Barrel Install/Removal Tool and a Magazine Well Block. If you only need a Magazine Well Block then a NoMar Magazine Block will be a cheaper alternative.

-Harbor Freight Diamond File Set

Sometimes you need a file a part to fit and these cheap files work very well. If you are not patient, don’t have a steady hands, or a precise eye, then DONT buy files. Remember to always file the cheaper part.

-Mark Brown Customs Gas Tube Gauge

-Needle Nose Pliers

-Schuster Sling Staking Tool

-2# Hammer

For removing Taper Pins

-1/2″ Tip Punch

For removing Taper Pins

-Propane Torch

For removing stuck/seized parts. MAP Gas is better but propane will work. Don’t get items cherry red.

-Canned Air

Turn it upside down and shoot liquid on parts you want to take apart or put together. Sometimes freezing a part is better than heat.

-1.4636 Forster .223 GO Headspace Gauge

-1.4736 Brownells 5.56 Field Headspace Gauge

This is made by Forster

-NoMar Rail Blocks or YHM Rail Blocks

These help alignment of Handguard Rails to the Upper Receiver when you are installing screws or tightening clamping bolts.

-½” Drive 2’+ Breaker Bar

For removing stuck Barrel Nuts.

-KNS Hammer Cage Tool

Good for people with large fingers, or those with arthritis.

-Digital Depth/Anvil Gauge

For quick and accurate Firing Pin Protrusion measurement.

-Midwest URR

I don’t recommend the Geissele Reaction Rod or the Kley Zion Clone. If you use a Torque Wrench, the Reaction Rod type devices are fine for Upper Receiver assembly, but if you plan on tearing down AR Uppers or changing Rails you really don’t want the Reaction Rod. The Reaction Rod is NOT good for trying to remove seized or overtorqued Barrel Nuts. Think about how the Reaction Rod works. It holds the Barrel in a static position but does NOT lock the Upper Receiver in place. If you have a stuck/seized Barrel Nut, the Upper Receiver will try to spin with the Barrel Nut. What keeps the Upper Receiver from spinning? The Barrel Index Pin does, and it will break off if you add too much force. Seen this countless times. This is why the Midwest URR is best tool for the job, it has a sail that locks into the charging handle slot, and teeth that lock into the barrel extension. These two features prevents the Upper Receiver and Barrel Extension from spinning. The Midwest URR is a gauge of sorts as well. If your upper is twisted, or the Barrel Extension is not timed properly, the tool won’t go into the upper properly. I have a video showing this issue from a few weeks ago. Clamshell Upper Receiver Blocks are great for removing a stuck/seized Barrel Nut, but the Clamshell Blocks won’t work on some billet Uppers Receivers, and you can’t use heat on the Barrel Nut without melting the Clamshell Blocks.

-PRI Gas Block Punch Block

Great for installing Gas Tubes in a Low Profile Gas Block

-Wheeler Bench Block

Works great for installing Roll Pins in the Trigger Guard, Charging Handle, and Bolt Catch. It can be used for removing FSB Taper Pins, but I don’t use it for that feature.

-Sinclair Bolt Vise

For removing Bolt Ejector and Reinstalling it. You can do this without a Bolt Vise but this tool simplifies the job.

-Sharpening Stone

For resurfacing/decking a Gas Key

-M-Guns MOACKS Staking Jig

There is no other good option. I have tried them all. I suggest you avoid using striking tools to stake from the side of the Gas Key. Doing so will stress the Gas Key Screws.

-Bondhus Metric & SAE Ball Tip Allen Drivers

-Blue Point Strap Wrenches

Best strap wrenches I have used.

-Timney Trigger Pull Gauge

-No-Mar or Brownells Hammer Drop/Dryfire Block

-.061-.250 Pin Gauge Set

That set will allow you to check the following:

Barrel Gas Ports, GO Spec for Bolt Firing Pin Hole (NO GO .070 requires a Taper Plug Pin Gage), GO Spec for Lower Receiver Hammer & Trigger Holes (NO GO.163 requires a Taper Plug Pin Gage), FCG Hammer & Trigger Holes, Carrier Key Bore, Cam Pin Bore, FSB/Gas Block Gas Tube Bore, GO Spec for Pivot & Takedown Bores (My NO GO Spec is .253, so that is outside the range of this Set).

You can’t do the following with this set:

Gas Block/FSB Barrel Journal Bore, and Bolt Carrier 3 Bore.

-Selector/Safety Bore

******************PROFESSIONAL LIST****************

-Brownells Apron or similar Apron

A good Apron is a must for a professional Armorer or Gunsmith.

-Hawkeye Bore Scope

This is for Barrel Inspection, Bolt Carrier Inspection, Suppressor and Muzzle Device Inspection, but most of all it’s great for aligning Gas Blocks. The Lyman Bore Scope is MUCH more affordable, but it’s not as clear and may not work well for Gas Block Alignment. I will be testing a very cheap alternative soon and if it works, I’ll update this post.

-Saturn Barrel Blocks

They grab like no other Barrel Blocks.

-.625 & .750 SLR or BRDE Barrel Dimple Jig

For Dimpling Barrels for Gas Block Set Screws. I recommend a drill bit collar and carbide bits to use these Jigs. A Drill Press or Mill is best but you can use a Hand Drill.

-Carbide Drill Bits for Dimple Jig

-PTG or Brownells Lapping Tool

Get training before using this tool.

-Brownells Magazine Lip Gauge

-Bushnell bore sighter/collimator

-Sweeny Site A Line Spud

Used with the Bushnell Collimator.

-Site Lite Bore Sight Laser

-Arisaka Leveling Kit

-CKT Level

-Badger Ordnance Dead Level

-.625/.750 Flex Hones

For deburring FSB and Gas Block bores

-Rotary Tool

Get training or practice A LOT before using this tool.

-Feed Ramp Rework Polish Kit:

-1/4″ Bullet Tip Stone (For cutting the Barrel Extension Ramps ONLY), #8 Cratex Bullet Coarse (Brownells Part # 190-025-081), #8 Cratex Bullet Fine (Brownells Part # 190-025-083), #4 Pointed Mandrel for Cratex Tips (Brownells Part # 190-001-004), 1/4″ x 3/8″ x 1/8′ Felt Bob (Brownells Part # 839-500-025), 555 Polish (For Felt Bob – Brownells Part # 080-555-001)

-M-Guns Throat Gauge

-BRT Gas Block Insert Tap Set

-PTG Muzzle Erosion Gauge

-Merchant/Brownells Throat Erosion Gauge

-PTG Barrel Straightess Gauge

-Schuster Thread Concentric Gauge

Checking for Thread to Bore Run-Out

-Geissele or Surefire Suppressor Alignment Rods

-Granite Slab

For checking for bent or untrue items.

-USGI Barrel Nut Wrench with 3 Prong F.H. Tool

-YHM Lock Ring Tool

-DPMS Armorers Tool

Needed for older Free Float Tubes and some Integrally Suppresed AR’s.

-Broken Shell Extractor or Cerro Safe

-Sight Adjustment Tool

-Law Tactical Tool

-AAC 3 Prong Flash Hider Tool

-Schuster Barrel Nut Alignment Rod

-Iron Pipe

Breaker Bar Extension

-Crows Foot Wrench Set

-Damaged Screw Extractors

-Two 3/32″ x 12″ Drill Rods

For Muzzle Device Alignment

-Geissele Gas Tube Punch Set

-Jewelers Screwdriver Cobalt 759897

-School of the American Rifle Firing Pin Hole Taper Plug Gauge

-School of the American Rifle Lower Receiver Hammer & Trigger Bore Taper Plug Gauge

******************INSANE LIST*************************

-Taps, Dies, & Handles

(Taps & Dies 1/4-28, 10-32, 8-32, 1 3/16-16, 1/2-28, 1/2-36, 5/8-24, 1 1/4-18)

-Tap Magic Aluminum

-Tap Magic Standard

-4-40 Tap

For Takedown Set Screw Modification

-NRA Trigger Weight Kit

-Stainless Shim Stock in .0005 and .0010

Barrel Extension Shimming/Bedding

-Number Drill Bit Set

-Campfire Wood Skewers

Put them in the bore when you have to open a Gas Port. When you see wood chips you know to stop.

-Drill Press/Mill

-Gunsmith Lathe

-Cut Away AR15

-Barrel Extension Install/Removal Tool & Barrel Vise

-Large Frame AR Tools

-Proprietary KAC AR Tools

-Additional AR Gauges (Gauges: Headspace, Barrel Straightness, Muzzle Erosion, Throat Erosion, Suppressor Alignment Gauge) (Calibers: .300 Blackout, .308, 7.62×51 NATO, 6.5 CM, 7.62×39, 6.5 Grendel, 6.8SPC, 9mm Luger, .458 SOCOM, .22 L.R.)

-Proprietary Barrel Nut Wrenches


-Ruby Stones

FCG Stoning and Deburring

-Brownells Castle Nut Tool

Good for old Style Castle Nuts & KAC Castle Nuts

-Impact Driver

For seized Fastners

-Present Arms Armorers Block Kit

Great for prefectly timed Receiver Extensions

-FCD Castle Nut Wrench

Needed for Present Arms Castle Nut work.

-.251-.500 Pin Gauge Set

-.501-.625 Pin Gauge Set

For measuring Takedown/Pivot NO GO, Bolt Carrier 3 Bore, Selector/Safety Bore

You can’t do the following with this set:

Block Barrel Journal Bore for the FSB/Gas Block

-Forster 11 Piece .223 Match Headspace Gage Set

-Mitutoyo 0-1″ Micrometer


-BRDE Universal Gas Plick Pin/Drill Jig

-Toaster Oven

For Thermal Fit items

-Bead Blasting Cabinet

-1 3/16-16 UN3B GO & NO GO Thread Gauge

For Castle Nut and Receiver Extension

-Parts Washer

-Bucket Heater

For Parts Washer

-Simple Green Precision (NOT regular Simple Green)

For Parts Washer

-Ultrasonic Cleaner

Suppressor Baffles and BCG Cleaning

-Air Compressor

-USGI Magazine Well Plug Gauge # 8439649

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