Convert a 1/2x28 9mm Host to a 3-Lug Suppressor Interface

The SilencerCo AC2604 3-Lug Muzzle Device adds a quick-attach 9mm 3-lug interface to compatible fixed-barrel firearms with 1/2x28 muzzle threads.

Rather than threading a suppressor directly onto the barrel each time it is installed, the AC2604 remains attached to the host firearm and provides the three-lug geometry used by a compatible 9mm 3-lug suppressor mount.

This type of setup is particularly useful on pistol-caliber carbines, subgun-style firearms and other fixed-barrel 9mm platforms where the suppressor may be installed and removed frequently.

AC2604: 1/2x28 Threads, 9mm Bore

SilencerCo manufactures several 3-lug muzzle-device variations for different thread pitches and calibers. This listing is specifically for:

• SilencerCo part number AC2604
• 1/2x28 barrel threads
• 9mm 3-lug interface

SilencerCo's current lineup also includes 1/2x36, 5/8x24 and metric-thread 9mm configurations as well as separate .45-caliber 3-lug muzzle devices. Verify the exact barrel thread before ordering.

Use Only with a 9mm 3-Lug Mount

AC2604 must be paired with a compatible 9mm 3-lug suppressor mount.

SilencerCo specifically states that its 9mm 3-lug muzzle devices must only be used with 9mm 3-lug mounts. The separate .45-caliber 3-lug system uses different dimensions and should not be mixed with this component.

The corresponding SilencerCo suppressor-side mount is the 9mm 3-Lug Mount, such as AC2447 where appropriate for the suppressor configuration.

Designed for Fixed-Barrel Hosts

SilencerCo describes the 3-lug system as a quick-attach mounting solution for firearms with fixed barrels.

Typical applications include:

• 9mm pistol-caliber carbines
• Subgun-style firearms
• Fixed-barrel 9mm platforms
• Other compatible 1/2x28 9mm hosts

A conventional recoil-operated handgun with a tilting barrel generally uses an appropriate piston / booster system instead of a rigid 3-lug configuration unless the suppressor and firearm manufacturers specifically approve another arrangement.

Fast Push-and-Rotate Suppressor Attachment

Once the firearm is equipped with a proper 3-lug muzzle device and the suppressor has the matching 3-lug mount installed, the system allows quick attachment and removal without repeatedly threading the suppressor directly onto the barrel.

For a dedicated 9mm PCC or subgun-style host, this keeps the muzzle interface compact and makes moving a compatible suppressor on and off the firearm considerably more convenient.

Current SilencerCo Compatibility

SilencerCo currently lists its 3-lug system for compatible configurations within several suppressor families, including:

• Omega K Series
• Spectre 9 Series
• Hybrid 46 — requires the appropriate Bravo Piston Mount
• Hybrid 46M — requires the appropriate Charlie Piston Mount
• Omega 36M — requires the appropriate Charlie Piston Mount

Compatibility ultimately depends on both sides of the system: the firearm must have the correct AC2604-compatible 9mm muzzle interface, and the suppressor must be configured with the appropriate 9mm 3-lug mount and any required mounting housing.

1/2x28 Is Common — But Confirm the Barrel

Although 1/2x28 is common on American-made 9mm barrels, it is not universal. Some 9mm platforms use 1/2x36, M13.5x1 LH or other thread specifications.

Verify the actual barrel thread, caliber, muzzle shoulder geometry and suppressor system before ordering.

A Useful Interface for a Dedicated 9mm PCC

The appeal of a 3-lug system is simplicity. Instead of leaving exposed barrel threads or repeatedly installing a direct-thread suppressor, the AC2604 gives the firearm a permanent compact mounting interface designed around fast suppressor attachment.

For shooters already using SilencerCo's 9mm 3-lug ecosystem, AC2604 is the factory option for a compatible 1/2x28 9mm fixed-barrel host.

Shop related SilencerCo products:
SilencerCo | Suppressor Muzzle Devices | SilencerCo Suppressor Accessories