The Forster Co-Ax priming mechanism is, in my opinion, fantastic. However, I as well as others have made a critical error during initial setup that results in improper seating depth. Those that RTFM rather than scanning it like I did are less likely to have this problem.
An Easy Adjustment
At issue is the jaws that hold the brass. Forster clearly states in the instructions “Based on the thickness of the case rim being primed…” when discussing how to perform the setup. In my case I somehow blitzed past this part and jumped to the dimensions shown in the image of the ends. In turn, I related the 0.054″ end to small primer, and 0.072″ to large. So much for attention to detail.
My first thoughts for the occasional high primer / FTF was to blame the press rather than the operator. Pretty lame, but that is how it went down.
If you are not sure if you are using the correct side of the jaws you can simply measure the thickness of the head, or slide a piece of brass under the jaw. When the brass is in the jaw, pull up on it a bit. You need to flip the jaws if the brass has more than a small amount of slack.
Using the correct jaws coupled with properly uniformed primer pockets all but guarantees consistent primer seating depth.