RADIAN UPPER 14.5″ 6MM ARC BROWN

Description

Radian Weapons built the Model 1 upper around a straightforward premise: that a complete upper receiver should require nothing more from the buyer than a compatible lower. Every component—charging handle, bolt carrier group, handguard, muzzle device—ships already fitted and assembled by a gunsmith who test-fires the unit before it leaves the shop. That approach suits the shooter who wants a finished, coherent system rather than a parts-bin build.

The 6mm ARC cartridge sits at the center of the design’s logic. It was developed to deliver a significantly higher ballistic coefficient than 5.56mm at similar chamber pressures, which means it holds velocity and resists wind drift further down range without requiring a larger platform. The 1:7 twist rate suits the heavier, longer-projection 6mm ARC projectiles that realize that ballistic advantage—lighter bullets in that bore diameter are rare enough that ammunition selection here is straightforward rather than a compromise.

Mid-length gas dwell time, relative to a carbine-length system on the same barrel, extends the interval before the bolt unlocks. That means chamber pressure has dropped further by the time the carrier begins moving, which softens the impulse the shooter feels and reduces the velocity at which components cycle. On a build intended for precision work at distance, that matters more than it does on a close-range carbine. The Dead Air KeyMo flash hider at the muzzle is machined to accept Dead Air suppressors without an adapter, so the transition to suppressed fire is a mount rather than a threading exercise. The Radian Raptor-SD charging handle and the 14-inch M-LOK handguard round out a package finished in Cerakote Brown throughout.