Armaspec Self-Retention Castle Nut AR-15/M4 7075-T6 Aluminum OD Green

The Armaspec Self-Retention Castle Nut is a purpose-built buffer tube castle nut designed for the AR-15 / M4 platform. Its self-retention geometry secures the castle nut to the buffer tube during installation, so it stays in place while you torque it down - no special tools, no staking, and no need for a third hand to keep everything aligned.

Machined from 7075-T6 aluminum for an excellent strength-to-weight ratio, this castle nut is finished in a hardcoat anodized OD Green for corrosion and abrasion resistance in the field. It threads onto a standard AR-15 / M4 buffer tube and provides the secure mounting point your rifle's stock depends on.

Whether you're building a new lower, replacing a lost or damaged castle nut, or simply upgrading from a standard unit, the self-retention design keeps the nut secured to the buffer tube throughout the install, making the build noticeably easier.