Daniel Defense DDM4®300 S Upper Receiver Group — Compact .300 BLK Performance

The DDM4®300 S Upper Receiver Group is a high-performance upper built for shooters who want a compact, fast-handling .300 Blackout platform while retaining the convenience of standard AR-15 magazines and bolts. This upper is built around a 262 mm Cold Hammer Forged S2W® profile barrel with a 1:8 twist and a pistol-length gas system, delivering increased muzzle energy from a short, maneuverable package. Note: this listing is for the upper receiver group only — not a complete rifle.

Daniel Defense designs components and complete systems to rigorous standards. This upper features CNC-machined 7075-T6 aluminum Mil-Spec upper receiver, a Chrome Moly Vanadium S2W® Cold Hammer Forged barrel that is chrome-lined and HP/MPI tested, a Daniel Defense DDM4 Rail 9.0 free-float handguard, and an M16-profile bolt carrier group — all engineered to provide durable, accurate performance from a compact form factor.

Overview of the DDM4®300 S Upper Receiver Group

• 262 mm Cold Hammer Forged S2W® barrel with 1:8 twist, pistol-length direct impingement gas system, chrome-lined and HP/MPI tested for durability and consistent accuracy.
• Designed for .300 Blackout while using standard 5.56 bolts and magazines to simplify logistics and compatibility.
• Mil-Spec CNC-machined 7075-T6 upper receiver with indexing marks and M4 feed ramps, Type III hard-coat anodized.
• DDM4 Rail 9.0 free-float handguard CNC-machined from 6061-T6 aluminum with M-LOK attachment points for lightweight, modular accessory mounting.
• Pinned low-profile gas block CNC-machined of 4140 hardened steel, mil-spec heavy phosphate coated (pistol-length gas).
• Muzzle device Daniel Defense Flash Suppressor, 17-4 PH stainless steel, salt-bath nitride finished.
• M16-profile bolt carrier group (mil-spec MP tested, chrome-lined, properly staked gas key) supplied as standard.
• Ambidextrous GRIP-N-RIP charging handle and DDM4 rail panels made from heat-resistant Santoprene for comfortable handling.
• Product weight: 1656 g; barrel length: 262 mm.
• Made in the USA