This 25-pack of spherical .67 caliber hard nylon plastic balls is ideally matched with the Ram-Shell cartridge. Insertion depth is near the base: use 20lb of force to seat.
This is a high velocity projectile, intended to deliver higher velocities than the rubber and blue nylon projectiles. By seating deeper in the hull, a higher pressure is obtained which generates higher velocity and generally cleaner burning of the charge.
Note that the diameter of these is close to the minimum that the Ram-Shell will retain consistently. In some cases it has been found to be benefical to add a very small strip of Painter's or Scotch tape to a section of the projectile to provide better retention.