I have the RF-100 and love it, you have to adjust the plastic stabilizer plate for small primers somewhat and change the primer size adapter...it's simple to change sizes really and you control the feed rate with the potentiometer adjustment located next to the on/off button. Safety wise this thing is engineered to high standards, it is a stout piece of machinery and the polycarbonate shroud is 1/4" thick, it is built very well. I usually have a tube full of primers waiting in the filler and the tray filled with 100ct of primers, when my low primer alarm goes off I grab the tube, dump the primers in the 650 and turn the primer filler on again and fill up the empty tube again, then dump more primers in the tray...rinse, repeat, rinse, repeat....