The RCBS AR Series die Set is a must for any progressive reloader. Each set comes packaged with a full length small base sizing die and a taper crimp seating die. With this combination reloading for an AR-style, semi-automatic, pump Action or lever action rifle just became a lot easier. Small base sizing dies size brass to minimum specifications and help to ensure that cartridges will chamber every time. The taper crimp seating die is helpful as it is a bit more forgiving die for crimping cases that have variable case lengths helping to reduce the number of bulges and buckled shoulders when crimping in bullets with a Cannelure. Due to the fact that this product sizes More than regular dies, it is crucial to have a sufficient amount of high quality lubricant to prevent stuck cases. These dies will also work with any single stage or turret press that will accept 7/8 inch -14 threaded dies. Type: 2 Die set fits: 308 Winchester note: uses shellholder #3 (sold separately).