Redding Reloading 300 Blackout Neck Die Set. The Neck Sizing Die is assembled with a decapping rod assembly with a neck sizing button. The conventional Seating Die contains a bullet guide built in crimp ring and proper seating plug. Please note that cases that have been neck sized only may not chamber in other firearms chambered for the same cartridge. Package Contents: Redding Reloading Neck Die Set for Bottleneck Cases Redding Reloading 82327: 300 Blackout Neck Die Set