Home / Buffer Tubes / Kits / ARCNUT AR15 Castle Nut ARCNUT AR15 Castle NutMSRP $8.99 AR15 Castle Nut 4140 Steel Mag Phosphate Finish MADE IN THE USA ARCNUT AR15 Castle Nut quantity Add to cart UPC: 765857617329 Categories: Buffer Tubes / Kits, Lower Parts Product ID: 383