I have a 1980 vintage rockchucker, and a 2012 vintage Co-Ax, and a 2022 vintage MEC Marksman. The MEC is smooth, like real smooth, to operate, no issues with primer disposal. Won't accept quik-change bushings and no on press priming. Out of the three of them, like the MEC the best, at the moment, as far as being smooth goes, like the shellholder setup too, works as advertised. I still use the other two, RCBS for rough stuff, depriming and pulling bullets, Co-Ax for sizing and the MEC for seating, although sizing is just as good on the MEC. I did pull the primer bottle off the Co-Ax and slightly flare the end of the tube and put a washer and an o-ring on it to keep it from falling off when I knock it with the knee.