Daniel Defense DDM4 GL/SSC SBR, 5.56 NATO, 12.5″ Barrel, FDE

Product Description

The Daniel Defense DDM4 GL/SSC SBR is a semi-automatic 5.56 NATO NFA short-barrelled rifle with a 12.5" Government profile cold hammer forged barrel, 1:7 twist, carbine-length gas system on a low profile gas block, the free-floating GL/SSC RIS II rail in FDE, a Timney AXCESS fire control group and a Daniel Defense flash hider.

GL/SSC stands for Grenade Launcher Sound Suppressor Capable, and the name describes the rail. Daniel Defense integrates all M203 grenade launcher mounting components directly into the rail itself — no additional parts, no special tools — while keeping the rail free floating so accessory loads and mounted hardware do not affect barrel harmonics. The same free-float hanger arrangement is what makes the rifle suppressor compatible without the rail fighting the can for space.

At 12.5 inches this barrel sits between the 10.3" MK18 length and a 14.5" carbine, and it is arguably the best compromise of the three for a suppressed 5.56: enough barrel to keep useful velocity and a manageable gas curve, short enough that adding a can does not produce an unwieldy rifle. This SKU also carries a Timney AXCESS fire control group in place of a Mil-Spec trigger, which is a genuine upgrade rather than a cosmetic one, and comes in FDE.

NFA short-barrelled rifle — how you buy it

This firearm is a short-barrelled rifle regulated under the National Firearms Act. It requires a BATFE tax stamp and an approved NFA transfer through a dealer holding a Special Occupational Tax stamp. Western Sport is an SOT dealer and completes these transfers regularly. No legal advice or timelines are given here — call 817-393-4000 and we will explain how it works through our shop. Our NFA firearms and suppressors categories cover what pairs with it.

Key Facts

• Brand / Model: Daniel Defense DDM4 GL/SSC
• Manufacturer Part Number: 02-088-22304-047 | UPC: 818773025317
• Legal category: NFA short-barrelled rifle (SBR) | Finish: FDE
• Action: Semi-automatic | Caliber: 5.56mm NATO
• Barrel: 12.5", Government profile, 1:7 twist, cold hammer forged
• Barrel material / finish: Chrome Moly Vanadium steel; chrome lined, Mil-Spec heavy phosphate coated
• Gas system: Carbine length, low profile gas block
• Muzzle device: Daniel Defense flash hider
• Muzzle thread: 1/2 x 28 TPI
• Rail: Free-floating GL/SSC RIS II, 11.5", FDE, with integrated M203 mounting components
• Fire control group: Timney AXCESS
• Compatibility: Suppressors and M203 mounting accessories via the free-float hanger system
• Weight: 6.2 lbs | Overall length: 29" – 32.25"
• Origin: Made in the USA

Why 12.5 inches is the suppressor sweet spot in 5.56

A 10.3" barrel is shorter but gives up more velocity and runs a harsher gas curve; a 14.5" barrel keeps velocity but a suppressor pushes overall length back toward a full rifle. At 12.5 inches with a can fitted you end up with something close to a 16" rifle’s footprint and most of its useful velocity. The rifle weighs 6.2 lbs bare, with an overall length of 29 to 32.25 inches depending on stock position. Browse muzzle devices before you commit to a mount.

Ordering from Western Sport in Roanoke, TX

Western Sport in Roanoke, Texas has been a Daniel Defense master dealer since 2007 and keeps a gunsmith on the premises. This firearm must be transferred to a licensed FFL, and as an NFA short-barrelled rifle that dealer must also hold an SOT and complete an approved NFA transfer with a tax stamp. We hold both licences. Call 817-393-4000.

Frequently Asked Questions

Q: What does GL/SSC stand for?

A: Grenade Launcher Sound Suppressor Capable. It describes the rail: Daniel Defense integrates all M203 mounting components directly into the free-floating GL/SSC RIS II rail, with no extra parts or special tools required, and the same hanger arrangement keeps the rifle compatible with suppressors.

Q: Does this rifle need a tax stamp?

A: Yes. With a 12.5-inch barrel and a shoulder stock it is a short-barrelled rifle under the National Firearms Act, requiring a BATFE tax stamp and an approved NFA transfer through a dealer holding a Special Occupational Tax stamp. Western Sport is an SOT dealer; call 817-393-4000 for details of our process.

Q: What is the Timney AXCESS fire control group?

A: An aftermarket-grade trigger group fitted to this SKU by Daniel Defense in place of a Mil-Spec trigger. It is one of the details that distinguishes this part number, and a meaningful one: trigger quality affects practical accuracy more than most component upgrades.

Q: Why choose 12.5 inches over 10.3 or 14.5?

A: It is the best balance for suppressed use. A 10.3-inch barrel loses more velocity and runs a harsher gas curve; a 14.5-inch barrel plus a can approaches full-rifle length. At 12.5 inches suppressed, the rifle keeps most of its useful velocity and stays close to a 16-inch rifle’s footprint.

Q: How heavy is the GL/SSC SBR?

A: 6.2 lbs, with an overall length of 29 to 32.25 inches depending on where the stock is set. The free-floating RIS II rail accounts for some of that weight, and the integrated M203 hanger system is part of why it is built the way it is.

Q: Can I really mount an M203 on it?

A: The rail integrates all M203 mounting components directly, which is the point of the design, but a grenade launcher is itself a regulated item and an entirely separate legal question that we will not advise on. Most buyers are here for the rail’s rigidity and suppressor compatibility.

Additional information