AR-15 notched crown castle nut in black billet aluminum. It secures the carbine-length receiver extension (buffer tube) and end plate to the lower receiver, with standard notches sized for both your armorer's wrench and a staking punch. Aluminum construction saves a small amount of weight versus a steel castle nut — a straightforward part on any AR-15 lower build.
Features:
Secures a carbine receiver extension and end plate on a mil-spec AR-15 lower. Aluminum is softer than steel — stake the nut with a punch after torquing so it cannot back off under recoil. Verify your buffer tube uses standard mil-spec threads (1.185"-18) before installing.
