Because of the many generations of Dillon 550 presses and the low-tolerance nature of the factory spent primer cup, some fitting may be necessary.
Install by pulling the press handle completely down and then removing the factory spent primer cup. Attach the FGS Engineering Dillon 550 Spent Primer Cup Shield by placing it on top. Replace the assembly back to the press and return the press handle to the normal position.
Some amount of “slop” is to be expected on the cup. Due to the shield’s design in combination with the spent primer catcher chute (Dillon part #13899), the cup should not become dislodged during normal operation.
Primer bar operating rod hits the cup – the operating rod bracket (Dillon part #13887) is too low on the primer housing. Loosen the bolt and move the operating rod bracket up until the operating rod clears the cup. The operating rod bracket should not be touching the top of your press. We have found a clearance of 1/8-1/4″ to be optimal.
Cup extremely too lose – Wrap one or more layers of invisible tape around the shield fits snugly onto the spent primer cup. Some may choose to permanently affix the knob using 2-part epoxy. Because of the solvents in some adhesives, use only a small amount when attaching. An excessive amount of glue could cause the PLA to melt/warp or otherwise give off dangerous fumes.
Cup too tight – Use 600 grit sandpaper to lightly sand the shield