RCBS® pioneered and developed 3-Die Sets for straight-wall rifle and pistol cases. The Carbide Sizer Die sizes the case and de-primes (the carbide sizer ring eliminates the need to lubricate). The Expander Die expands the case to the proper diameter to accept the bullet, and it imparts case mouth flare/bell for bullet feeding. The Seater Die seats the bullet and roll crimps.
This 3-die set comes with a sizing die, mouth expander die, and a seater die that also roll crimps. The roll crimp is important in high-recoiling revolvers to prevent the bullet from pulling out of the case under recoil potentially causing a cylinder jam.
