What is a front sight gas block for an AR-15?

A front sight gas block combines a standard gas block with an integrated or attached front sight, simplifying your rifle build and allowing for iron sight use without a separate front sight.

Will a front sight gas block fit my barrel?

Most front sight gas blocks are designed for .750” barrel diameter. Always verify the size of your barrel’s gas journal before purchasing.

Can I co-witness iron sights with these gas blocks?

Yes. Be sure to choose the correct sight height—F-marked for standard setups or gas block height for matching with your rear sight to ensure proper co-witness.

Do any of these gas blocks have bayonet lugs?

Yes. Select A2-style front sight gas blocks include bayonet lugs for military clone or traditional builds.

What’s better: folding or fixed front sight gas blocks?

Folding sights are ideal for use with optics and backup scenarios, while fixed sights offer simplicity and rugged durability for co-witnessed setups or iron-sight-only builds.

AR-15 Front Sight Gas Blocks – Fixed, Folding & Railed Options

Name: AR-15 Front Sight Gas Blocks
Brand: Mounts Plus
Availability: InStock

Folding Front Sight Gas Block

Railed Gas Block Front Sight

**A.R.M.S. #41-LUG Optional Baynoet Lug for #41-B** $16.00

**A.R.M.S. Silhouette #41-BL Folding Front Sight with Bayonet Lug** $203.00

**A.R.M.S. #41B Silhouette Folding Front Sight** $203.00

**PRI Flip up Front Sight with .750" gas block** $186.00

**PRI .625 Gas Block Flip Up Sight** $191.00

**Samson Quick Flip FFS-EXT - Railed Gas Block Folding Front Sight** $92.96

**Yankee Hill Flip Front Sight Gas Block with Bayonet Lug (.750")** $144.50

AR-15 Front Sight Gas Blocks – Fixed & Folding Sight Combos for Your Rifle

Upgrade your AR-15 with a front sight gas block designed for performance, precision, and reliability. Whether you're restoring a classic A2-style rifle, building a custom tactical setup, or looking for a low-profile gas block with iron sight backup, Mounts Plus offers a comprehensive selection of AR-15 front sight gas blocks to meet every shooter’s needs.

Choose from fixed, folding, and railed front sight gas block combos, built from durable materials and engineered to provide solid mounting and consistent zero retention in every environment.

🔩 Top AR-15 Front Sight Gas Blocks We Offer

Product Name	Type	Features
YHM Flip-Up Front Sight Gas Block	Folding	Bayonet lug, mil-spec height
Samson Quick Flip FFS-EXT Front Sight	Folding	Extended gas block height
PRI Folding Front Sight Gas Block Combo	Folding + Rail	Precision machined, .750 fit
M1S A2 Front Sight Gas Block	Fixed (F-marked)	Bayonet-compatible, pinned style
CMMG Low Profile Gas Block with Front Sight Rail	Low-Profile + Rail	Clamp-on, lightweight

✅ Compatible with .750, .625, and other common barrel diameters
✅ Choose from A2 fixed sight, flip-up, or railed front gas blocks
✅ Designed for direct fit on standard AR-15 gas systems

⚙️ Why Choose a Front Sight Gas Block Combo?

✔️ Combines two essential components – Save weight and simplify your setup
✔️ Ideal for iron sight backups – Perfect for co-witnessing or BUIS setups
✔️ Enhanced durability – Secure attachment means consistent point-of-aim
✔️ Available with bayonet lug – Maintain full M4-style functionality
✔️ Cleaner profile – Great for builds without free-floating handguards

Whether you’re retrofitting a service rifle clone or refining a duty setup, the right front sight gas block gives you rugged reliability and modern flexibility.

🔍 Popular Applications & Configurations


Use Case	Recommended Gas Block Type	Key Features
Military Clone Build	Fixed A2 Sight with Bayonet Lug	Traditional look and function
Tactical / BUIS Setup	Folding Flip-Up Sight Gas Block	Low-profile and backup ready
Lightweight Custom AR	Railed Gas Block + Detachable Sight	Flexible optic & iron combo
Suppressed Setup	Low-Profile with Flip Sight (adjustable)	Works with suppressor gas tuning

🔧 Installation Tips

Barrel Diameter Fit – Most gas blocks fit .750” barrels; check specs for other sizes
Mounting Style – Choose clamp-on or set-screw depending on barrel finish
Gas Port Alignment – Ensure precise alignment for proper cycling
Torque Screws Properly – Apply blue thread locker and torque to ~25 in-lbs
Check Sight Height – Match with rear sight height (F-marked or gas block height)

❓ Frequently Asked Questions

Q: What is a front sight gas block?
A: It's a combo component that replaces the standard gas block and includes a built-in or attached front sight, eliminating the need for separate parts.

Q: Will these fit my AR-15 barrel?
A: Most of these gas blocks are for .750” barrels, the most common AR-15 profile. Always check your barrel diameter before purchase.

Q: Are these compatible with standard rear sights?
A: Yes. Be sure to choose the correct height: F-marked (standard) or gas block height to ensure proper co-witnessing.

Q: Can I mount a bayonet with these?
A: Only gas blocks with a bayonet lug—typically A2-style or military clone sights—allow bayonet mounting.

Q: What's better: fixed or folding front sight gas block?
A: Fixed sights are simple and rugged; folding models offer flexibility when using optics.

🔗 Related Accessories

🛒 Why Mounts Plus?

✔️ Wide selection of top-tier front sight gas blocks
✔️ Brands like YHM, Samson, PRI, and CMMG
✔️ In-stock and ready to ship from our U.S. warehouse
✔️ Trusted by builders, professionals & LE since 1994
✔️ Expert customer support from real shooters

🔥 Build It Right. Hit Your Mark.

Your AR-15 deserves a front sight gas block that enhances both form and function. Whether for backup sights, precision setups, or military-style builds, Mounts Plus has the gear you need.

➡️ Shop AR-15 Front Sight Gas Blocks Now at Mounts Plus
➡️ Reliable. Rugged. Ready to Shoot.