You need to tune your RF100. Adjust the upward pointing screw at the top; and adjust th angle of the clear plastic guide to match your primer type. Suble differences in primers require tweaks.
I tuned that thing like I was tuning up a 1957 Les Paul. It's working now, but not as smooth as the other one. The rheostat is janky as well. QC apparently varies on the RF100. I'm just giving hope for those who have been victim shamed when they get a bad one. Some come ready to rock, but others not so much.