The RCBS AR Series Small Base Taper Crimp 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. The small base sizer die sizes brass to minimum specifications and helps to ensure that cartridges will chamber every time. The small die is designed for semi-automatic firearms. The taper crimps eating die is helpful as it is a bit more forgiving die for crimping cases that have variable case lengths, reducing the number of bulges and buckled shoulders. Made out of durable steel.