The Radical Firearms 5.56mm Upper (brand part no. RF00325) is a complete, mil-spec AR-15 upper chambered in 5.56 NATO/.223 Remington, built around a 16-inch barrel with a 1-in-7 twist rate and topped with an M-LOK handguard. Because the upper is built to mil-spec dimensions, it drops onto any standard mil-spec AR-15 lower receiver without additional fitting or gunsmithing. The 1-in-7 twist stabilizes heavier, longer 5.56 bullet weights, giving the upper flexibility across a range of ammunition choices. Radical Firearms builds this upper for shooters finishing out a build or upgrading an existing rifle, whether they are novice or advanced shooters wanting to hit the range with a reliable, ready-to-run setup.

Key Specifications

• Chambered in 5.56 NATO/.223 Remington for broad ammunition compatibility.
• 16-inch barrel clears the federal rifle minimum for use under a fixed or adjustable stock.
• 1-in-7 twist rate stabilizes heavier, longer 5.56 bullet weights.
• M-LOK handguard adds mounting space for lights, grips, and optics.
• Built to mil-spec dimensions for drop-in fit on any standard AR-15 lower.
• Sold as a complete upper, ready to install.

Frequently Asked Questions

Will this upper fit any AR-15 lower? Yes, it is built to mil-spec dimensions and drops onto any standard mil-spec lower.

What twist rate does it use? A 1-in-7 twist, suited to heavier, longer 5.56 bullet weights.

Is this a good option for a first build? Yes, it is designed as a complete, ready-to-run upper for novice and advanced shooters alike.

Buy the Radical Firearms 5.56 Upper

Finish your build with a versatile, mil-spec 5.56 upper ready for the range. Order this Radical Firearms upper from our AR15 uppers selection, and our Lubbock, Texas team will get it shipped fast.