Adjustable Gas Blocks

Faxon Firearms’ patented adjustable gas blocks are engineered around a simple reality of AR rifles: carbon fouling kills adjustability.

Instead of placing the adjustment screw directly in the gas stream—where heat and carbon quickly cause seizing—Faxon’s patented design repositions the adjustment mechanism away from direct gas-port carbon exposure. This anti-fouling geometry keeps the adjustment screw cleaner, freer-moving, and tunable over time, even on suppressed and high-round-count rifles.

Once tuned, a dedicated mechanical locking interface physically resists rotation, ensuring the setting stays put through heat cycles, recoil, and vibration.

Machined from 4140 steel, finished with flash nitride, and secured using a three-point clamping system, these gas blocks are built as a complete, purpose-designed tuning system—not a wear item.

Adjust cleanly. Lock confidently. Keep it that way.

Why Faxon Adjustable Gas Blocks Rank Different in Real-World Use

Most adjustable gas blocks fail for one reason: the adjustment screw sits where it gets hammered by heat and carbon. Faxon’s patented system is designed to fight that from the start by positioning the adjustment mechanism away from direct gas-port carbon exposure, helping reduce carbon-induced seizing and keeping adjustments consistent over time.

Patented anti-fouling adjustment geometry

By avoiding direct gas-port carbon contact, the adjustment stays cleaner and remains tunable longer—especially on suppressed and high-round-count rifles.

Mechanical lock that resists movement

Once tuned, a dedicated locking interface helps the setting stay put through heat cycles, recoil, and vibration—not just “thread friction”.

Built like a system, not a wear item

  • 4140 steel construction for strength at the gas system’s highest-heat point
  • Flash nitride finish for corrosion resistance and durability
  • Low-profile footprint designed to fit under most modern free-float handguards
  • 3-screw mounting for stable, repeatable alignment on the barrel journal
  • 14 tactile settings (variant dependent) from fully open to fully closed for precise tuning
Use-case clarity: If you’re tuning for a suppressor, an SBR, or multiple ammo types, your goal is consistent function with the least excess gas. These gas blocks are built to help you dial cycling and recoil to your exact barrel/ammo/buffer/suppressor combination.

Choose the Right Journal Size

Adjustable gas blocks must match your barrel’s gas journal diameter. Faxon adjustable gas blocks are offered in the most common sizes for AR-pattern barrels.

Journal Size Best Fit / Common Use
.625" Lightweight/pencil profiles and many hunting/fast-handling builds where a smaller journal is used. Confirm your barrel journal with calipers or the barrel spec sheet.
.750" The most common AR-15 journal size across general-purpose, duty, and many performance barrels. Ideal for suppressed tuning due to broad compatibility.

How to Tune for Suppressed vs. Unsuppressed

Suppressed (typical goal):
  • Reduce excess gas and bolt speed
  • Minimize blowback and improve comfort
  • Decrease parts wear over long round counts
Unsuppressed (typical goal):
  • Reliable lock-back on empty magazine
  • Consistent feeding with your chosen ammo
  • Balanced recoil impulse for faster follow-ups
Practical tuning tip: Start more open, confirm reliability (including lock-back), then close down in small increments until function is consistent with the lowest excess gas.

Explore Related

Shop Adjustable Gas Blocks

FAQs

What makes Faxon’s adjustable gas block resist carbon fouling? ▾

Faxon’s patented anti-fouling design places the adjustment mechanism away from direct gas-port carbon exposure, helping reduce carbon-induced seizing and keeping adjustments consistent over time—especially on suppressed rifles.

How many adjustment settings do these gas blocks have? ▾

Many Faxon adjustable gas block variants feature 14 tactile settings from fully open to fully closed. Check the individual product listing to confirm the adjustment range for that specific model.

Which journal size do I need—.625" or .750"? ▾

Your gas block must match your barrel’s gas journal diameter. .750" is the most common AR-15 journal size, while .625" is often used on lightweight/pencil-profile barrels. Confirm your barrel specs or measure the journal before ordering.

Is this suitable for suppressed rifles? ▾

Yes. Adjustable gas blocks are an ideal solution for suppressed setups because they let you reduce excess gas and bolt speed, which can help minimize blowback and improve overall shooting comfort while maintaining reliable cycling.

What tools do I need to adjust the gas setting? ▾

Most Faxon adjustable models can be adjusted using a 3/32" Allen key or a flathead screwdriver. Refer to the individual product page for the exact tooling callout.

Will this fit under my handguard? ▾

These blocks use a low-profile footprint intended to fit under most modern free-float handguards. If your rail has unusually tight internal clearance, verify the handguard’s internal diameter before installation.

Are Faxon gas blocks made in the USA? ▾

Yes. Faxon Firearms is a family-owned American manufacturer producing components in Greater Cincinnati, Ohio, with engineering and machining roots dating back to 1978.

Warranty

All Faxon Firearms products are backed by our Limited Lifetime Warranty.
For full warranty terms, service instructions, and exclusions, please visit:
https://faxonfirearms.com/warranty-privacy-terms/