Very old thread...but. I've had pretty good luck with .223, 6.5cm, 308 and like cartridges....but once I wanted to automate my my 300PRC...I ran into some problems. I had to have the loading arm swing up much higher to get the arm angled to where the very long 300PRC case wasn't hanging up due to the case mouth too flat hitting the ejector and binding up. However, if I went too high up...the white plastic knobs underneath would bind as well...and keep the whole assembly horizontal instead of up where the ejector could eject it.
Took some smoothing out the shellholder as well. I got it dialed in finally....and now it will run pretty good without supervision while I'm doing other tasks. Here is a very short shaky cam view of it with the 300PRC.