CMMG AR-15 Front Sight Base — F-Style
Model: 55DA3EA • UPC: 810046232224 • Type: F-marked front sight base (FSB) for flat-top AR-15 uppers
Give your carbine a durable, fixed front sight that’s always ready. The CMMG AR-15 Front Sight Base, F-Style (55DA3EA) is purpose-built for modern flat-top receivers, providing the correct F-height sight plane for reliable zeroing with standard rear BUIS and many optics co-witness setups. Machined for hard duty and precise alignment, this FSB anchors your gas system and delivers a rock-solid, repeatable front sight reference—no batteries, no drift, no excuses.
Why Choose an F-Style Front Sight Base
Correct F-Height for Flat-Tops: F-marked sight bases sit slightly taller than legacy A2 bases to preserve mechanical zero on M4/flat-top carbines with typical rear sights.
Always-On Durability: Fixed steel front sight resists impact and heat far better than most flip-ups—ideal for training, patrol, and defensive carbines.
Gas System Anchor: Serves as both the front sight and the gas block, with a proven, rigid interface for dependable cycling.
Optic Friendly: Works with red dots and prisms for absolute or lower-1/3 co-witness (varies by mount height and rear sight).
Serviceable Standard: Accepts common A2-pattern front sight posts, springs, and detents, making adjustments and replacements simple.
Key Features & Fit Notes
Style: F-marked front sight base for flat-top receiver height
Material: Steel construction for strength and heat resistance
Function: Combines gas block and fixed front sight in one unit
Compatibility: Designed for the AR-15 platform; pairs with most standard rear BUIS
Barrel Journal: Typical FSBs fit common journal sizes (e.g., .750" on many carbines) — verify your barrel diameter and pin spacing before purchase
Attachment: Front sight bases are commonly taper-pinned to the barrel for maximum security; some barrels require gunsmith drilling/reaming
Small Parts: Sight posts, detents, springs, taper pins, and handguard caps may be sold separately—check your package contents
Important: AR-15 barrels vary in journal diameter, gas port location (carbine/mid-length/rifle), and pin spacing. Confirm your exact barrel specs and whether it is pre-drilled for an FSB.
Real-World Benefits
Consistent Zero: Metal-on-metal interface and pinned installation resist shifts from heat, drops, and barricade pressure.
Training-Proof: Fixed front sight is visible at all times—no deployment step to forget under stress.
Simple Adjustments: Standard A2 post provides tactile elevation clicks with widely available tools/spares.
Weather Resistant: Steel construction handles rain, grit, and temperature swings without losing zero.
Ideal Use Cases
Duty/Defensive Carbines: Dependable, always-ready aiming reference paired with a rugged gas system.
Training & Classes: Survives thousands of reps, sling abuse, and barricade work.
Classic Builds: Perfect for M4-style and “KISS” rifles with fixed rear sights or carry-handle rears.
Co-Witness Optic Setups: Aligns with many red dots for quick sight confirmation and backup aiming.
Installation Overview (Pro Tips)
Verify Specs: Confirm barrel journal (.750" or other), gas system length, and pin spacing.
Align Gas Port: Seat the FSB so the gas port lines up precisely—gas misalignment = short-stroking.
Pinning: Most FSBs require taper-pin drilling/reaming using a fixture. Professional installation is strongly recommended.
Torque & Check: If your setup uses set screws (some barrels/FSBs do), clean/degrease, apply thread locker, and dimple the barrel where appropriate.
Sight In: Zero the front sight with your chosen rear (25/50/100-yard methods) and confirm with your optic co-witness, if used.
Compatibility & Accessory Notes
Rear Sights: Works with carry handles and most folding rear BUIS designed for flat-top receivers.
Handguards: Ensure handguard cap compatibility if your build uses one; free-float rails typically omit caps.
Muzzle Devices: Installing/removing some muzzle devices may be easier before the FSB is pinned in place.
Bayonet Lug/Hardware: Presence of lugs or caps varies by specific FSB pattern—review the product photos/contents.
Care & Maintenance
Wipe carbon from the sight tower and gas block area during routine cleaning.
Keep the front sight post lightly oiled to prevent corrosion and ease adjustments.
After hard impacts or high-heat sessions, confirm your zero and inspect pin fit.
SEO Highlights (Quick Copy)
CMMG AR-15 F-Style Front Sight Base for flat-top carbines
F-marked height for correct zero with standard rear BUIS
Steel, gas-block + front sight combo for durability
Model 55DA3EA, UPC 810046232224
Compatible with A2 front sight posts; ideal for M4-style builds
Frequently Asked Questions
Q: What’s the difference between F-style and A2 height?
A: F-style is slightly taller to match the height over bore of flat-top carbines. Using an A2 base on a flat-top often forces the front post very high to zero—or may not zero at all.
Q: Will this fit my barrel?
A: It’s designed for AR-15 barrels that accept a front sight base. Verify your journal diameter (.750", .625", etc.), pin spacing, and gas system length before you buy.
Q: Are the taper pins and small parts included?
A: Contents can vary by listing. Check whether taper pins, A2 post, detent, spring, and handguard cap are included or need to be purchased separately.
Q: Can I install it at home?
A: Proper FSB installation usually requires specialized jigs and taper-pin reamers. For best results, use a qualified gunsmith.
Safety Reminder
Always ensure your firearm is unloaded before installation. After any sight or gas system work, function-check and re-zero the rifle with your chosen ammunition and rear sight/optic.
Lock in proven reliability and a true mechanical backup with the CMMG AR-15 Front Sight Base, F-Style (55DA3EA, UPC 810046232224)—the durable, correctly-sized front sight and gas block solution for flat-top carbines that demand a rock-solid zero.
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