Troy 13.8 TRX 308 Ext DPMS

Product Description

The Troy 13.8 TRX 308 Ext DPMS is a handguard extension designed for DPMS-pattern .308 AR rifles. This 13.8-inch rail section extends the mounting surface on your rifle, adding attachment points for accessories forward of your existing handguard. It’s built for shooters running larger-frame AR platforms who need more real estate for lights, grips, or bipods without replacing the entire handguard.

Handguard extensions bolt on ahead of a factory rail, creating a continuous or stepped platform depending on your base handguard profile. The TRX 308 Ext is machined to fit DPMS-pattern .308 receivers, the most common large-frame AR standard in civilian and custom builds.

Key Facts

• Product Name: Troy 13.8 TRX 308 Ext DPMS
• SKU: TY-STRX-E3D-13BT-00
• Platform Compatibility: DPMS-pattern .308 AR rifles
• Length Designation: 13.8 inches

What the TRX Extension Does

A handguard extension solves a specific problem: you want more rail space, but you don’t want to tear down your gas system or remove a factory handguard that’s already installed and zeroed. The TRX 308 Ext mounts forward of your existing rail, anchoring to the barrel nut or a dedicated extension collar depending on your setup.

This approach works well for hunters and precision shooters who add a bipod far forward for better stability, or for tactical shooters staging a light and laser out past the support hand position. Extensions also let you run a suppressor under the rail without the can protruding into your sight picture.

DPMS-Pattern .308 AR Compatibility

The TRX 308 Ext is cut for DPMS-pattern receivers, which use a specific barrel nut thread and upper receiver dimension. DPMS-pattern guns are the most widely produced .308 AR platform and include rifles from Aero Precision, Palmetto State Armory, CMMG, and many custom builders. This is distinct from the Armalite AR-10 pattern, which uses a different barrel nut thread pitch.

If you’re running a large-frame AR and unsure which pattern you have, the barrel nut thread will tell you. DPMS uses the same 1-3/16″-16 TPI thread as the AR-15. Call 817-393-4000 to confirm fitment if you’re unsure which receiver pattern your rifle uses.

Installation and Accessory Mounting

Handguard extensions typically require removal of the muzzle device and sometimes the gas block, depending on your barrel profile and the extension’s inner diameter. Some builders use a clamp-on collar behind the extension to bridge the gap between the factory handguard and the extension rail. Others replace the barrel nut entirely with an extended version that supports both the original handguard and the extension.

Once installed, the TRX 308 Ext gives you additional mounting slots for M-LOK accessories, Picatinny rail sections, or direct-attach bipods and grips, depending on the attachment interface Troy machines into this model. Confirm the specific rail type and slot pattern before ordering accessories.

Buying from Western Sport in Roanoke, TX

Western Sport is a licensed FFL/SOT dealer and gunsmith shop serving the North Texas and DFW area since 2007. Owner and gunsmith Lance Rankin handles installations, custom builds, and transfers on site. Call 817-393-4000 to confirm specifications, check compatibility with your rifle, or place an order.

Frequently Asked Questions

What does the TRX 308 Ext fit?

The TRX 308 Ext fits DPMS-pattern .308 AR rifles. DPMS-pattern receivers use a 1-3/16″-16 TPI barrel nut thread and are the most common large-frame AR standard. This extension will not fit Armalite AR-10 pattern rifles, which use a different thread pitch and upper receiver spec.

How does a handguard extension attach to the rifle?

Handguard extensions mount forward of your existing handguard, typically anchoring to the barrel nut, a separate extension collar, or directly to the barrel depending on the system design. Installation usually requires removing the muzzle device and may require gas block removal depending on clearance. Call 817-393-4000 if you need installation assistance or want to confirm the mounting method for this model.

Can I use this extension with a suppressor?

Many shooters use handguard extensions specifically to cover a suppressor, keeping the can under the rail and out of the sight line. Whether this 13.8-inch extension will cover your suppressor depends on your barrel length, muzzle device length, and suppressor body length. Measure your setup before ordering, or call 817-393-4000 for fitment advice.

What is the difference between DPMS and Armalite AR-10 patterns?

DPMS-pattern and Armalite AR-10 pattern rifles are both .308 AR platforms, but they use different barrel nut threads, bolt carrier profiles, and upper receiver cuts. DPMS is the more common pattern and uses the same barrel nut thread as the AR-15. Parts are not interchangeable between the two patterns, so confirm your receiver type before ordering any barrel nut, handguard, or extension.

Do I need a gunsmith to install a handguard extension?

Installation depends on your mechanical skill and tools. You’ll need a barrel nut wrench, vice, upper receiver block, and torque wrench at minimum. Some extensions require timing or headspace checks depending on how they interface with the barrel nut. Western Sport offers gunsmithing services in Roanoke, TX if you prefer professional installation. Call 817-393-4000 to schedule.

How do I order this rail from Western Sport?

You can order the Troy 13.8 TRX 308 Ext DPMS through our online shop or by calling 817-393-4000. Western Sport is located in Roanoke, Texas, serving the DFW and North Texas area. We handle transfers, special orders, and can answer compatibility questions before you buy.

• Weight w/barrel nut: 13.06oz.
• Weight w/o barrel nut: 11.51oz.
• Exact Length: 13.8”
• Number of rail slots: 34
• Inner diameter: 1.61”
• Outer diameter: 1.8”
• Diameter of cooling hole: .5”
• Number of cooling holes: 10
• Gas tube channel diameter: .5”
• Gas tube channel height: .43”-HP, .35”-LP
• Inner diameter of barrel nut: 1.24”
• Material: 6061 T6 Aluminum
• Coating type: MIL-A-8625 Type III Class 2 Hard Coat Anodized w/ Teflon