After the inspection station, the case is ready to receive the projectile. Potential problems in seating bullets in a high-speed environment are
- inverted projectiles,
- misalignment, which can cause case damage.
Mechanical loaders operate too fast for an operator to hand-feed bullets into the mouths of charged cases. Bullets must be mechanically fed, requiring a dedicated station upstream of the bullet seater. To avoid inverted projectiles, a discriminator (that either turns all bullets the same direction or rejects any that are improperly oriented) must be installed in the feed mechanism.
To avoid misalignment problems, the seater die (that pushes the bullet to its final position) is fitted with a sliding sleeve having an inside diameter a few thousandths of an inch larger than the bullet diameter. Even if the bullet is tipped when placed on the case, the sleeve aligns it vertically, ensuring that the bullet heel does not snag on the case mouth.
Once the bullet is aligned in the sleeve, a seating punch moves down the sleeve and contacts the nose of the bullet. Pressure seats the bullet, and a stop ring on the punch sets the proper seating depth.