RADIAN UPPER 18″ 6MM ARC BROWN

Description

Radian’s 18-inch 6mm ARC upper is built for the shooter who wants meaningful reach from an AR-platform rifle without stepping up to a larger action. The 6mm ARC cartridge was developed specifically for the AR-15 bolt face, so it feeds and cycles through a standard-size upper while delivering external ballistics that hold up at extended distances — flatter trajectory and better wind resistance than what most conventional AR calibers offer at the same case size.

The rifle-length gas system is the right choice for an 18-inch barrel in this role. Compared to a mid-length or carbine setup on the same tube, it delays the port opening longer, which bleeds off less pressure before the bullet exits and spreads the recoil impulse over a longer rearward stroke. The practical result is a softer, more deliberate cycle that is easier to stay on target through and gentler on the bolt carrier group over time.

A 1:7 twist rate stabilizes heavier, longer projectiles — the bullets that most fully exploit 6mm ARC’s ballistic potential at range. Shooters who handload or select match ammunition around 103- to 108-grain bullets will find this twist well suited to that end of the caliber’s capability.

The 17-inch M-LOK handguard gives enough rail space to run a full-length sight radius, a bipod, and any support accessories without crowding. The Dead Air KeyMo muzzle brake is retained by the same mounting interface used by Dead Air suppressors, so the brake serves as a functional device that also doubles as a mounting point if the owner runs compatible Dead Air cans. The Radian Raptor-SD charging handle and Radian Enhanced Bolt Carrier Group are fitted from the factory, and the entire assembly is finished in Cerakote Brown.