← AR-10 / .308 AR reference page · This work order as JSON ·
Work order — AR-10 / .308 AR
Taking the firearm apart for a job such as refinishing, and putting it back together to specification. Generated from the Pew-Takedown entry last updated 2026-10-29. Confidence: medium.
| Work order # | |
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| Model on the bench | |
| Serial number | |
| Finish / colour | |
| Received | |
| Technician |
Before you startEducational guide only. Some information comes from non-authoritative sources. Always consult your manufacturer's manual and a licensed gunsmith. Verify your firearm is unloaded before every procedure.
- This work order is written for the AR-10 / .308 AR. It is reported to cover DPMS LR-308 pattern rifles; Armalite AR-10 pattern rifles; SR-25 pattern rifles — if the firearm on the bench is one of those, check the torque notes: values do not always carry over.
- No manufacturer torque values are recorded. The values listed are reported by other sources, not the manufacturer — confirm them before use.
Shop difficulty: Tier 2 of 3
A large-frame AR with 63 key numbers (18 upper, 37 lower, 8 bolt carrier), so it strips like an AR-15 with heavier springs. It has the same detent and roll-pin traps, a highly compressed operating spring, and a barrel nut that needs the armorer's wrench, vise block and torque wrench. ArmaLite has headspace checked by a gunsmith if the barrel or bolt changes. 63 parts (ArmaLite AR-10 (7.62 NATO): upper 1-18, lower 1-37, bolt carrier 1-8; bolt and charging handle as assemblies; variant rows marked * not counted). Pew-Takedown's rating, not the manufacturer's.
Bench time: strip ~45 min, rebuild ~65 min (estimate). Actual: strip ______ rebuild ______
Special tools:
- Upper receiver vise block / reaction rod — Holding the upper for barrel nut and muzzle device work
- AR armorer's wrench (barrel nut/castle nut) — Barrel nut and receiver extension castle nut
- Torque wrench (ft-lb and in-lb) — Barrel nut, castle nut, muzzle device
- Pivot pin detent installation tool (or 3/32" punch) — Holding the pivot pin detent while the pin goes in
- Roll-pin starter punches (1/16", 3/32", 1/8") and a bench block — Bolt catch, trigger guard, forward assist and ejection port cover pins
- Lower receiver vise block — Supporting the trigger guard ears and bolt catch boss
Watch for:
- The large-frame operating spring is under high compression and can get away during disassembly or reassembly. (both; ArmaLite, Inc.)
- The front pivot pin and rear takedown pin each sit on a spring-loaded detent that launches when the pin comes out; reinstalling the pivot pin means holding the detent down while the pin goes in, which is the classic AR lower trap. (both; Shooting Illustrated (NRA))
- The TM has the armorer use a pivot pin tool to compress the detent, and warns to catch the detent and spring as the pin comes out. (both; Department of the Army)
- The bolt catch and trigger guard roll pins mar the receiver unless the receiver is taped and supported and a roll-pin starter punch is used. (both; The Firearm Blog)
1. Clear and make safe
- Point the muzzle in a safe direction and keep your finger off the trigger.
- Press the magazine release and remove the magazine.
- Pull the charging handle fully rearward and lock the bolt back.
- Inspect the chamber and magazine well with a light, then physically confirm the chamber is empty.
- Place the selector on SAFE if the hammer is cocked, and remove all live ammunition from the work area.
2. Disassemble
Field Strip
- Complete the Clear and Make Safe procedure and release the bolt forward.
- Push the rear takedown pin from the left side to its captured position.
- Pivot the upper receiver forward on the front pivot pin.
- Push the front pivot pin out and separate the upper from the lower receiver.
- Pull the charging handle partway rearward and withdraw the bolt carrier group.
- Pull the charging handle down and out of its channel.
Warning: Carrier first, then charging handle. - Remove the firing pin retaining pin, tip out the firing pin, rotate and lift the cam pin, and withdraw the bolt.
Warning: Keep the cam pin with the rifle. A rifle assembled without it is dangerous.
3. Refinish
The components the procedures above separate. Coating, masking and cure are outside this database; follow your coating system's instructions. A part the manufacturer marks "factory fit" should not be swapped or reworked.
| Component separated | Out | Coated | Back in |
|---|---|---|---|
| Upper receiver assembly | |||
| Bolt carrier group | |||
| Charging handle | |||
| Firing pin | |||
| Cam pin | |||
| Bolt |
No manufacturer statement of materials or finish is recorded. Identify each part's material before choosing prep and cure.
4. Reassemble
Reassembly
- Insert the bolt into the carrier, push it fully in, drop the cam pin into its hole and rotate it 90 degrees.
- Drop the firing pin in tail first and install the firing pin retaining pin.
Warning: If the retaining pin will not go in, the cam pin is missing or unrotated. - Insert the charging handle, then the carrier, and slide both fully home.
- Mate the upper to the lower, press both pins home.
- Charge the rifle and perform the function check.
5. Torque
No manufacturer torque values are recorded for this firearm.
Reported by other sources — not the manufacturer
Not a manufacturer specificationConfirm with the manufacturer or a licensed gunsmith before use. Where these differ from a manufacturer value above, the manufacturer wins.
| Fastener | Reported value | Sequence | Source | Applied | Init. |
|---|---|---|---|---|---|
| Barrel nut (MI-CR308 barrel nut, replacing factory barrel nut and delta ring) .308 AR (AR-308) fitted with a Midwest Industries MI-CR308 handguard Reported by Midwest Industries, Inc. (secondary) — not the manufacturer |
max. 50 ft-lb 67.8 N·m · 600 in-lb |
Grease the receiver threads, install the MI-CR308 barrel nut hand tight, then torque with the provided ½" drive barrel nut wrench to 50 ft lbs (DO NOT EXCEED). | [2] PDF p. 1 (PDF p. 1) | ||
| Handguard clamp bolts (2) with torque plate .308 AR fitted with a Midwest Industries MI-CR308 handguard Reported by Midwest Industries, Inc. (secondary) — not the manufacturer |
40 in-lb 4.5 N·m · 3.3 ft-lb |
Drop the torque plate in the handguard clamp; install screws; tighten the receiver-end bolt first; torque while ensuring proper alignment. 'DO NOT INSTALL AND TIGHTEN THESE SCREWS WITH OUT THE TORQUE PLATE.' | [2] PDF p. 1 (PDF p. 1) | ||
| Barrel nut (Aero Precision M5E1 barrel nut) Aero Precision M5E1 (AR-10/.308) upper receiver Reported by Aero Precision (secondary) — not the manufacturer |
65 ft-lb 88.1 N·m · 780 in-lb |
AR15 mil-spec barrel-nut wrench. | [4] p. Barrel Nut Torque Specifications | ||
| Handguard screws (Aero Precision M5 Enhanced Gen 2, Torx T15) AR-10/.308 (Aero M5) with an Aero Precision M5 Enhanced Gen 2 handguard Reported by Aero Precision (secondary) — not the manufacturer |
25 in-lb 2.8 N·m · 2.1 ft-lb |
[4] p. Screw Torque Specifications | |||
| Barrel nut (Aero Precision M5 R-ONE / S-ONE handguard barrel nut) Aero M5 (AR-10/.308) upper with an Aero Precision ATLAS R-ONE or S-ONE M5 handguard Reported by Aero Precision (secondary) — not the manufacturer |
35–65 ft-lb 47.5–88.1 N·m · 420–780 in-lb |
The article gives one torque range for R-ONE/S-ONE and notes the M5 versions use a standard armorer's wrench instead of the wrench extension; shims to reach gas-tube alignment. | [5] p. article body | ||
| M-LOK rail-section screws on the handguard (MI-CR308) AR-308 / AR-10 with a Midwest Industries MI-CR308 handguard Reported by Midwest Industries, Inc. (secondary) — not the manufacturer |
15 in-lb 1.7 N·m · 1.2 ft-lb |
[2] PDF p. 1, step 11 (PDF p. 1) | |||
| Barrel nut (ODIN Works 308 M-LOK forend barrel nut) AR-10 with an ODIN Works 308 M-LOK forend (installed with the 1 3/8" jumbo crowfoot) Reported by ODIN Works (secondary) — not the manufacturer |
40–50 ft-lb 54.2–67.8 N·m · 480–600 in-lb |
[6] p. Features | |||
| Barrel nut (Faxon Streamline AR10 handguard, DPMS high profile) AR10 (DPMS high-profile .308 upper) with a Faxon Streamline Aluminum M-LOK AR10 handguard Reported by Faxon Firearms (secondary) — not the manufacturer |
max. 50 ft-lb 67.8 N·m · 600 in-lb |
1-3/8" wrench. Faxon: 'DO NOT OVER-TIGHTEN.' | [7] p. Installation Instructions | ||
| Handguard clamp screws (Faxon Streamline AR10) AR10 (DPMS high-profile) with a Faxon Streamline Aluminum M-LOK AR10 handguard Reported by Faxon Firearms (secondary) — not the manufacturer |
32 in-lb 3.6 N·m · 2.7 ft-lb |
Re-check torque after the first live-fire test. | [7] p. Installation Instructions | ||
| Barrel nut — final torque (BATTLEARMS RIGIDRAIL) AR-10 with a BATTLEARMS RIGIDRAIL free-float handguard Reported by Battle Arms Development, Inc. (BAD / BATTLEARMS) (secondary) — not the manufacturer |
45 ft-lb 61 N·m · 540 in-lb |
After the 40 ft-lb pass and loosening one-half turn; ceiling 50 ft-lb. | [8] PDF p. 2, step 8 (PDF p. 2) | ||
| Rail retention clamp hex bolts (2) (BATTLEARMS RIGIDRAIL) AR-10 with a BATTLEARMS RIGIDRAIL free-float handguard Reported by Battle Arms Development, Inc. (BAD / BATTLEARMS) (secondary) — not the manufacturer |
30 in-lb 3.4 N·m · 2.5 ft-lb |
Alternate between the two bolts until both stop rotating at the set torque. Threadlocker: Blue Loctite recommended on the hex bolts. |
[8] PDF p. 3, step 13 (PDF p. 3) | ||
| Receiver extension (Magpul UBR GEN2 buffer tube) into the lower receiver SR25/M110-pattern (AR-10) lower with a Magpul UBR GEN2 stock Reported by Magpul Industries Corp. (secondary) — not the manufacturer |
35–39 ft-lb 47.5–52.9 N·m · 420–468 in-lb |
Hold the buffer retaining pin depressed while threading the tube in; 1/2" torque driver in the square recess. Magpul cites US Army TM 9-1005-319-23&P for the value. Threadlocker: None — 'DO NOT USE LOCTITE OR OTHER LOCKING COMPOUND ON RECEIVER EXTENSION THREADS.' |
[9] PDF p. 4 (PDF p. 4) | ||
| UBR GEN2 Main Tube Nut SR25/M110-pattern (AR-10) with a Magpul UBR GEN2 stock Reported by Magpul Industries Corp. (secondary) — not the manufacturer |
20–25 ft-lb 27.1–33.9 N·m · 240–300 in-lb |
Included adapter tool plus an armorer's (castle-nut) wrench. | [9] PDF p. 5, step 7 (PDF p. 5) |
Notes: The manufacturer's documents give no torque value. They say: "WARNING: EXCESSIVE TIGHTENING OF THE LOCK RING WITH A STRAP WRENCH CAN LOOSEN THE BARREL NUT OR DEFORM THE GAS TUBE." (Operator's Manual — Rifle, 7.62mm SuperSASS / Carbine, 7.62mm SuperSASS (ArmaLite AR-10 SuperSASS), PDF p. 48) "To install the backup sights, slip the base over the receiver or gas block, and tighten down until firm by using a 7/32" hex head wrench" (Operator's Manual — Rifle, 7.62mm SuperSASS / Carbine, 7.62mm SuperSASS (ArmaLite AR-10 SuperSASS), PDF p. 11 (section 5.1))
Fit or check on rebuild
- Headspace after barrel or bolt change — ArmaLite: headspace must be checked by a qualified gunsmith if the bolt carrier assembly or barrel is replaced (printed on the upper parts list image)
- Barrel nut torque and gas tube alignment — The barrel nut is torqued within a range and indexed for the gas tube
- Function check (safety, hammer reset, disconnector) — The hammer spring orientation and disconnector seating are checked with a function check
- Sight/optic re-zero — The front sight base, rail or optic moves when the barrel/handguard comes off
6. Function check
- Verify the rifle is unloaded with no magazine inserted before each step.
- Charge the rifle, place the selector on SAFE, and press the trigger. The hammer must not fall.
- Move to SEMI and press the trigger. The hammer should fall.
- Hold the trigger back, charge the rifle, release slowly and listen for the disconnector.
- Confirm the bolt locks back on an empty magazine.
If any check fails, the firearm is not safe to fire. Stop and see a licensed gunsmith.
Sources
- AR-10 / LR-308 Pattern Rifle Owner’s Manuals (various manufacturers) — Various primary
- MI-CR308 Installation Instructions — Midwest Industries, Inc. secondary
https://midwestindustriesinc.com/content/installation-instructions/AR308-MI-CR308-Instructions.pdf - Operator's Manual — Rifle, 7.62mm SuperSASS / Carbine, 7.62mm SuperSASS (ArmaLite AR-10 SuperSASS) — ArmaLite, Inc. (© 2006) — scan hosted on archive.org primary
https://archive.org/details/gunmanual_Armalite_AR10_Super_Sass - Aero Precision Support Center — Torque Specifications (article updated 2024-04-01; read via the help centre's Zendesk API because support.aeroprecisionusa.com refused the TLS handshake from this environment) — Aero Precision secondary
https://support.aeroprecisionusa.com/hc/en-us/articles/14130432684951-Torque-Specifications - Aero Precision Support Center — How to install a R-ONE/S-ONE Handguard (updated 2025-01-09; read via the help centre's Zendesk API) — Aero Precision secondary
https://support.aeroprecisionusa.com/hc/en-us/articles/14130449931671-How-to-install-a-R-ONE-S-ONE-Handguard - ODIN Works 1 3/8" Jumbo Crowfoot Wrench (for ODIN Works 308 MLOK Forend installation) — product page — ODIN Works secondary
https://www.odinworks.com/1-3-8-Jumbo-Crow-Foot-Wrench-p/acc-1-3-8-crowfoot-308.htm - Faxon Streamline Aluminum M-LOK 15" AR10 Handguard (DPMS High Profile) — product page 'Installation Instructions' (same text on the 6.5" and 10.5" pages) — Faxon Firearms secondary
https://faxonfirearms.com/FFHGMLOK15G310 - BATTLEARMS RIGIDRAIL Free Float Rail Handguards for the M16 . M4 . AR-15 or AR-10 Weapon Platforms — Instructions (maker's PDF re-hosted by distributor OpticsPlanet; no copy found on battlearmsdevelopment.com) — Battle Arms Development, Inc. (BAD / BATTLEARMS) secondary
https://www.opticsplanet.com/i/pdf/opplanet-battle-arms-development-rigidrail-ar15-m16-free-float-rail-handguards-installation-pdf.pdf - Magpul UBR GEN2 Collapsible Stock — Installation & Usage Instructions for the AR15/M4 & SR25/M110 (072-0105-B) — Magpul Industries Corp. secondary
https://magpul.com/media/wysiwyg/Instructions/MAG482_UBR_GEN2_Stock%20INSRT.pdf - The AR-10 Story — American Rifleman (National Rifle Association) secondary
https://www.americanrifleman.org/content/the-ar-10-story/ - ArmaLite AR-10 / AR-10B Owner's Guide — ArmaLite, Inc. primary
https://s3.amazonaws.com/files.ammunitiondepot.com/armalite-rifles/owners-manuals/armalite-ar10-ar10b-owners-guide.pdf - AR Lower Receiver Build: Pivot Pin Installation — Shooting Illustrated (NRA) secondary
https://www.shootingillustrated.com/content/ar-lower-receiver-build-pivot-pin-installation/ - TM 9-1005-249-23&P, Rifle, 5.56mm, M16 and M16A1 (unit and direct support, incl. RPSTL) — Department of the Army primary
https://archive.org/download/ArmyTechnicalManualforM16Rifle-Tm9-1005-249-23p/Manual-Tm9-1005-249-23p_djvu.txt - TFB Armorer's Bench: Complete AR15 Assembly - Lower Receiver — The Firearm Blog secondary
https://www.thefirearmblog.com/blog/2022/07/31/tfb-armorers-bench-complete-ar15-assembly-lower-receiver/
| Reassembled and function-checked by | Date |
|---|
Educational guide only. Some information comes from non-authoritative sources. Always consult your manufacturer's manual and a licensed gunsmith. Verify your firearm is unloaded before every procedure. Full disclaimer: https://github.com/Fundamental-build-LLC/Pew-Takedown
Legal notice: this material is third-party information compiled from sources of varying reliability and is provided for general informational and educational purposes only. It is not gunsmithing, technical, safety or legal advice, it is not verified or endorsed by any manufacturer, and it must not be taken as fact. Any work on a firearm beyond the routine field stripping described in its own owner's manual should be performed only by a licensed and insured gunsmith. You use this material entirely at your own risk. Fundamental Build LLC and the project's contributors make no warranty of any kind and accept no liability for death, injury, damage or loss arising from its use. Full terms: LEGAL.md.