Main problem is that dropper assembly use brass weight to seat a bullet into case. Sometimes this force is not big enough to properly seat a bullet into case. When I was using Mr. Bullet feeder without MARK-7 this was not so annoying. I got dropped bullet about every 50 rounds so not a big deal. But when I purchased MARK-7 this problem made me crazy and I got a lot of jams and spilled powder. My solution to a problem is to increase bullet seating force with spring rather than weight. So upgrade product is born.