I had my first Co-Ax by 1980. For priming on top it uses shell holders that, except for having a larger hole through the center, are identical to RCBS's. I picked up a second one with the modern "universal" sliding side shell holder but only because it was $25 out the door. A local gun store that sells a lot of used reloading tools did not know it was a reloading tool.
I bought my first Co-Ax as a step up from a Rock Chucker. It is primarily for bottle neck rifle cases. For loading pistol cartridges faster than a single stage I had a C-H press. It moved 4 RCBS type shell holders up and down between two pillars. C-H's deluxe carbide die sets came with 4 shell holders. While the H press is long gone the Co-Ax is still unequaled.