LBE Unlimited AR-15 Castle Nut, 4140 Steel, Black Phosphate

The LBE Unlimited Castle Nut (LBE Unlimited part no. ARCNUT) is a black phosphate-coated, 4140 steel castle nut built for AR-15 platform buffer tubes. LBE Unlimited machines it to lock the receiver extension, or buffer tube, securely against the lower receiver, which is what keeps a collapsible or fixed stock from working loose over time. It’s a small, inexpensive part, but the right one matters: a stripped, cracked, or missing castle nut can leave your entire stock assembly loose on the gun.

Key Specifications

• Machined from 4140 steel.
• Finished with a black phosphate coating for corrosion resistance.
• Compatible with AR-15 platform buffer tubes.
• Functions as the castle nut, locking the receiver extension against the lower receiver.

Frequently Asked Questions

What does a castle nut do? It locks the buffer tube, or receiver extension, securely against the lower receiver, keeping the stock assembly from working loose.

Will this fit my AR-15? Yes, it’s sized for standard AR-15 platform buffer tubes.

Buy the LBE Unlimited AR-15 Castle Nut

A loose stock assembly is often just a worn or damaged castle nut, and this LBE Unlimited nut is a cheap, direct-fit way to tighten everything back down. Order from our Lubbock, Texas gun shop and it ships fast to your door, along with more AR buffer system parts.