| Category | Required Tools |
|---|---|
| Assembly Essentials | Armorer's Wrench, Punch Set, Vise Block (Upper & Lower), Torque Wrench (in-lb & ft-lb) |
| Optic Installation | Wheeler FAT Stix or inch-lb driver, Scope leveling kit, Blue Loctite (242/243), Anti-seize for dissimilar metals |
| Diagnostics & QC | Headspace gauges (GO/NO-GO), Borescope, Bore guide, Carbon fiber cleaning rod |
| Consumables | Blue Loctite 242/243, Rocksett, Aeroshell 33MS, CLP/lubricant |
The right tools make the difference between a rifle that runs and one that doesn't. This guide covers every tool you need to build, maintain, and mount optics on AR-pattern rifles—plus when and how to use each one.
This guide assumes familiarity with these topics:
These are the foundational tools for any AR build. Whether you're assembling a lower receiver or installing a handguard, you'll reach for these constantly.
A multi-purpose wrench designed for AR-15 castle nuts, barrel nuts, and free-float handguard installation. Look for one that fits MIL-SPEC castle nuts and has provisions for common barrel nuts.
Get a wrench with a built-in torque adapter or pair it with a 1/2" drive torque wrench. The Magpul Armorer's Wrench and Real Avid Master-Fit are both solid choices that cover most barrel nut styles.
Roll pin punches, starter punches, and pin punches in various sizes for driving out and installing pivot pins, trigger pins, and detent pins. Brass or polymer-tipped punches prevent marring on finished receivers.
Use a roll pin holder or needle-nose pliers to start roll pins. Striking them directly with a punch often leads to bent pins or marred receivers. The Wheeler Roll Pin Install Tool Kit makes this nearly foolproof.
Clamshell blocks that hold upper or lower receivers securely in a bench vise without damaging the finish. Upper vise blocks fit the magazine well; lower blocks clamp around the receiver body or use the takedown pin holes.
Standard clamshell upper vise blocks transfer barrel nut torque through the receiver's index pin. For high-torque barrel nuts (50+ ft-lbs), use a reaction rod or Geissele Super Reaction Rod that loads the barrel extension lugs instead. This prevents cracking the upper receiver.
You need two types: a foot-pound wrench for barrel nuts and castle nuts, and an inch-pound wrench for optic mounts, gas block screws, and grip screws. Digital or click-type both work—pick what fits your budget.
The core tools for building AR lowers, installing uppers, and mounting handguards. These are the most-used tools in any armorer's kit.
A rugged all-in-one wrench covering castle nuts, barrel nuts, and most proprietary handguard nuts. The 1/2" drive hole accepts torque wrenches.
Universal wrench with interchangeable heads for different barrel nut patterns. Works with most proprietary rail systems.
Complete punch set with starter punches, roll pin punches, and brass drift punches to avoid marring receivers.
Precision-ground steel punches with brass and polymer tips for sensitive work on coated receivers.
Barrel extension-engaging rod that absorbs torque through the lugs, not the receiver's index pin. Essential for high-torque barrel nuts.
Dual-purpose block that holds uppers and lowers. Can also engage barrel extension for torque work, though not as robust as a reaction rod.
1/2" drive click-type torque wrench for barrel nuts (30–80 ft-lbs) and castle nuts (35–40 ft-lbs). CDI and Tekton are both reliable choices.
Purchasing through these links may generate a commission at no extra cost to you. Always verify torque specs for your specific components.
Mounting optics correctly requires precision. A crooked reticle or improperly torqued rings will cost you accuracy and repeatability. These tools ensure your optic is level, properly torqued, and stays put through thousands of rounds.
A canted reticle introduces tracking errors that compound at distance. Leveling systems use dual bubbles or laser projection to align the scope reticle with the rifle's bore axis before you torque the rings.
Optic mount screws, ring screws, and red dot mounting screws all require precise inch-pound torque values. Over-torquing can crack scope tubes, strip threads, or warp red dot housings.
The Wheeler FAT Stix set includes preset torque limiters at common values. Pop in the right stick, turn until it clicks, and you're at spec. Faster than adjusting a wrench and nearly impossible to over-torque.
Blue Loctite (242/243) is your go-to for optic mount screws, gas block screws, and grip screws. It prevents vibration loosening while remaining removable with hand tools. Anti-seize is used on dissimilar metals (steel screws in aluminum mounts) to prevent galling.
Precision tools for mounting red dots, LPVOs, and scopes without damaging rings or over-torquing mounting screws.
Torque sticks preset at common values (15, 25, 35, 65 in-lb). Click, stop, and you're at spec. Includes common Torx and hex bits.
Compact torque limiters that work with any 1/4" bit. Mix and match torque values for optics, gas blocks, and muzzle devices.
Dual-bubble system that aligns the scope reticle with the rifle's bore axis before you torque the rings.
Projects a laser grid onto a wall to align your reticle perfectly before torquing. Faster than dual-bubble in well-lit spaces.
Medium-strength threadlocker for optic mount screws, gas block screws, and grip screws. Prevents vibration loosening while remaining removable.
Includes alignment bars, thread locker, lubricant, and cleaning gear for proper scope mounting. A good starter kit if you're new to optics.
Purchasing through these links may generate a commission at no extra cost to you. Always follow manufacturer torque specs for your specific optic.
These tools help you verify safety-critical dimensions and inspect wear over time. Essential for armorers managing multiple rifles or anyone building from parts.
Headspace is the distance from the bolt face to the chamber shoulder that stops the cartridge. Incorrect headspace can cause case head separations, extraction failures, or dangerous pressure spikes. Check headspace when swapping bolts or barrels.
If the bolt closes on a NO-GO gauge, the rifle has excessive headspace and is unsafe to fire. Do not use it until you've replaced the barrel or bolt to bring headspace into spec. A FIELD gauge represents the maximum safe limit—if it closes on that, stop immediately.
A digital borescope lets you inspect the bore, chamber, throat erosionThroat Erosion[Barrel]Gradual wear at the chamber end of the barrel from hot propellant gases. Affects accuracy over thousands of rounds by changing the bullet's jump to the rifling., and gas port condition without disassembly. Side-view probes are ideal for AR barrels since they let you see the rifling lands and grooves clearly.
Always clean from chamber to muzzle. A bore guide centers the cleaning rod in the receiver and prevents solvent from seeping into the action. Carbon fiber rods won't embed grit like steel rods can.
Tipton's carbon fiber rods with bearing handles follow the rifling twist automatically, reducing rod flex and wear on the crown. Pair with a quality bore guide and you'll never damage your throat with a cleaning rod again.
Tools for safety inspections, bore condition assessment, and armorer-level maintenance. Essential when swapping bolts or barrels.
Precision-ground gauges to verify chamber dimensions. Check headspace after swapping bolts or barrels, or during semi-annual inspections.
Digital borescope with side-view probe for inspecting bore condition, throat erosion, and chamber fouling without disassembly.
Centers cleaning rods in the receiver to protect the throat and chamber. Seals the action to keep solvent out of the trigger mechanism.
Carbon fiber won't embed grit like steel rods. Bearing handle follows rifling twist automatically to reduce rod flex.
Purpose-built scraper for cleaning carbon from bolt tails, cam pin pockets, and firing pin channels.
Purchasing through these links may generate a commission at no extra cost to you. Consult a qualified armorer if you're unsure about inspection results.
These products get used up over time but make assembly reliable and keep rifles running. Stock up on the essentials and rotate through your supply.
Products that get used up over time—threadlockers, lubricants, solvents, and spare parts. Stock up and rotate through your supply.
Water-soluble ceramic adhesive for muzzle devices. Survives suppressor heat but can be removed by soaking in water.
Mil-spec grease for barrel nut threads, buffer tube threads, and any steel-on-aluminum interface. Prevents galling and seizing.
Odorless, non-toxic CLP for general cleaning, light lubrication, and corrosion protection. Safe on all finishes.
Extreme-duty lubricant designed for high-temp suppressed use. Doesn't burn off like petroleum lubricants.
Aggressive copper fouling remover for stubborn jacket deposits. Use when standard CLP isn't cutting through copper streaks.
Selector detent springs, buffer retainer springs, and pivot pin detents. Keep spares on hand—these love to fly across the room during assembly.
Purchasing through these links may generate a commission at no extra cost to you. Store chemicals per manufacturer guidelines.
Always check manufacturer specs—some proprietary systems (Geissele, BCM, LaRue) have different requirements. When in doubt, start at the low end of the range and verify the fastener holds under recoil before going higher.
All-in-one kits that cover most or all of your AR build needs. Great for getting started without buying tools piecemeal.
Entry-level kit with armorer's wrench, punch set, vise block, and basic tools. Covers most first-build needs.
Comprehensive kit with upgraded punches, universal wrench heads, torque tools, and storage case. Covers serious builds and fleet maintenance.
Budget-friendly starter kit with basic tools. Quality is entry-level—plan to upgrade punches and wrenches over time.
Compact, field-portable kit with torque limiters, bits, and essential tools. Perfect for range bags or go-boxes.
Purchasing through these links may generate a commission at no extra cost to you. Individual tool quality may vary—upgrade key items as needed.
Got your tools? Put them to work with our other guides:
This guide is for educational purposes. Always follow manufacturer instructions and torque specifications for your specific components. If you're unsure about any procedure, consult a qualified armorer or gunsmith. Purchasing through affiliate links may generate a commission at no extra cost to you.
Ready to continue? Here's the recommended next guide:
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