Fortis Manufacturing Standard Castle Nut – AR-15/AR-10 Compatible

The Fortis Manufacturing Standard Castle Nut secures the receiver extension (buffer tube) to the lower receiver on AR-15 and AR-10 platform rifles. This mil-spec replacement part maintains proper tension on the buffer tube threads and provides staking points for the end plate, preventing loosening under recoil. Whether you're replacing a worn castle nut or building a new lower receiver, this component ensures reliable operation and proper buffer system function.

Machined from steel with a manganese phosphate finish for corrosion resistance. Features standard mil-spec dimensions and staking notches. Installation requires an AR-15 armorer's wrench and proper torque (35-40 ft-lbs recommended). Staking the castle nut to the end plate after installation is standard practice to prevent rotation.

• Part Type: Castle Nut
• Compatible Firearms: AR-15, AR-10, and other AR-pattern rifles
• Material: Steel
• Finish: Manganese Phosphate
• Installation: Requires AR-15 armorer's wrench and torque wrench; staking recommended
• Includes: (1) Castle Nut