CMMG M16 Extractor Pin — Mil-Spec Replacement for AR-15/M16/M4 Bolt Carrier Groups (Part 55BA431 | UPC 810046235195)
Keep your rifle running with confidence. The CMMG M16 Extractor Pin is a mil-spec replacement component for AR-15/M16/M4 bolt assemblies, engineered to secure the extractor to the bolt and deliver reliable, repeatable extraction under hard use. Whether you’re rebuilding a high-round-count bolt carrier group, refreshing critical small parts, or stocking spares for your range kit, Part #55BA431 gives you precise fit, durable metallurgy, and dependable retention you can trust.
Why choose the CMMG 55BA431 Extractor Pin
Mil-Spec Fit & Tolerances: Built to the dimensions armorers expect so it drops in and locks the extractor consistently on standard AR-pattern bolts.
Durable Steel Construction: Heat-treated pin resists peening and deformation from repeated cycling, preserving extractor alignment and spring tension.
Secure Extractor Retention: Proper diameter and finish reduce galling and ensure smooth pivot of the extractor for consistent case control.
Smart Spare to Carry: A tiny part with a big job—keep one in your grip core, field kit, or armorer box to quickly revive an out-of-service BCG.
CMMG Quality: From barrels to small parts, CMMG is known for reliable manufacturing and compatibility across mainstream AR builds.
What it fixes & prevents
Worn or mushroomed pins that can loosen extractor movement and cause erratic extraction/ejection.
Inconsistent tension from misfit or out-of-spec pins leading to stovepipes or failures to extract.
Unexpected downtime at matches or classes—swap a suspect pin in minutes and keep shooting.
Compatibility
Platforms: AR-15/M16/M4 bolt assemblies using M16-pattern extractor hardware (direct-impingement and many piston ARs).
Bolts: Designed for standard 5.56/.223 bolts; many 300 BLK and 350 Legend bolts share the same extractor pin spec.
Note: Always confirm compatibility on non-standard or caliber-specific bolts (e.g., some large-frame or proprietary systems).
Installation (quick guide)
Verify unloaded. Separate upper and lower; remove BCG and field strip the bolt.
Control the extractor spring/insert. Using a punch, push the old pin out while retaining the extractor.
Inspect & clean. Check extractor, spring, and O-ring/insert; clean the pin bore.
Reinstall. Seat the extractor on the bolt, align the holes, and press the new pin through until flush on both sides.
Function check. Confirm free extractor pivot and positive tension; reassemble and test.
Pro tip: Replace the extractor spring and insert on the same schedule as the pin for maximum reliability—especially on short gas systems and suppressed setups.
Maintenance & service life
Inspection interval: Check at cleaning or every 1,000–2,000 rounds for peening or walk-out.
Lubrication: A light film of oil prevents corrosion and eases removal during future services.
Keep spares: Pins are inexpensive insurance—store extras with your gas rings, firing pin retaining pins, and ejector springs.
Specifications
Brand: CMMG
Part: M16 Extractor Pin
Part Number: 55BA431
UPC: 810046235195
Material: Hardened steel (mil-spec pattern)
Finish: Protective coating for corrosion resistance
Use: Secures extractor to bolt in AR-pattern BCGs
What’s in the package
(1) CMMG M16 Extractor Pin 55BA431
(Extractor, spring, insert, and other components sold separately unless noted by the retailer.)
Who it’s for
Enthusiasts & competitors building reliability-focused ARs
Armorers & range staff standardizing maintenance parts
Prepared shooters who carry mission-critical spares
SEO-friendly keywords (use naturally on your product page)
CMMG M16 extractor pin, 55BA431, AR-15 extractor pin replacement, AR bolt extractor hardware, mil-spec extractor pin 5.56, CMMG small parts, BCG repair parts, UPC 810046235195.
Small part, big reliability. Keep your AR cycling cleanly with the CMMG M16 Extractor Pin (55BA431)—a precise, durable replacement that locks in dependable extraction for thousands of rounds.
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