Quick view Austin Custom Brass Backbores Austin Custom Brass MSRP: $95.00 - $102.50 Austin Custom Brass Backbores All ACB tops and backbores utilize the now universally accepted "Warburton" threads, making them compatible with almost every other maker's modular components! Check... Qty in Cart: 0 Price: MSRP: $95.00 - $102.50 Subtotal: Options