The Daniel Defense M4 Complete Upper in .300 AAC Blackout (brand part number 23-088-19020-047) ships as a fully assembled 10.3-inch upper receiver group, ready to drop onto a compatible lower without a separate barrel, bolt carrier group, or handguard purchase. Daniel Defense builds these complete uppers with the same components and quality control that goes into their full rifles, giving builders a shortcut to a .300 Blackout build without sourcing parts individually. This upper ships with no sights, so an optic or set of iron sights still needs to be added separately.

Key Specifications

• Chambered in .300 AAC Blackout.
• Barrel measures 10.3 inches.
• Rifled with a 1:8 twist rate, suited to a wide range of .300 AAC Blackout bullet weights including heavier subsonic loads.
• Ships as a complete upper receiver group, ready to install on a compatible lower.
• Sold with no sights included, so an optic or iron sights must be added separately.
• Built with the same components and quality control Daniel Defense applies to its complete rifles.

Frequently Asked Questions

Does this upper come with a bolt carrier group and charging handle? Yes, it ships as a complete upper receiver group; no sights are included, so an optic or iron sights need to be added separately.

Is a 10.3-inch .300 Blackout upper an NFA item? No. This is an upper receiver group only, with no lower receiver included, so it is not itself a regulated firearm. Installing it on a rifle-configured (shouldered stock) lower without proper registration would create a short-barreled rifle, so it should only be paired with a pistol-configured lower or a properly registered SBR lower.

What lowers is this upper compatible with? Any standard mil-spec AR-15 lower receiver, provided the overall configuration complies with federal short-barrel regulations.

Buy the Daniel Defense M4 Complete Upper, .300 AAC Blackout, 10.3in

Add a complete .300 Blackout upper to your build without sourcing parts one at a time. Order the Daniel Defense M4 Upper from our Lubbock, Texas gun shop for fast, insured shipping and complete your AR15 upper build.