Lets see, Dillon 550. manual advance, progressive. Is it possible to advance the table twice, due to being distracted, or something, not dropping a powder charge?
I’ll have to admit, not being a fan of a manual indexing press, why I owned more than one of all the other Dillon’s and a progressive from just about everyone that sells one today before I bought a 550. That said if you can walk and chew gum at the same time, it’s not a problem.
Can you advance the shell plate twice? Sure, you will have thrown a case into the bin with no crimp, advanced a case into the crimp station with no bullet, put a case into #3 without powder and have nothing in #1 or #2. Would likely be obvious to even a blind person that knows Braille.
Same thing for double charge, if you always have a bullet to be seated with your indexing had (left one) and grab a case with the right one between strokes, you can’t forget to index either or you will seat two bullets in #3 and somehow get two cases in the shell plate at #1.
After owning one, I figure it’s a “problem” that people that don’t own one bring up.
Now, I have read about all sorts of stuff causing powder charging problems. Folks running the old (non fail safe) linkages, June bugs, spiders and even one where a live primer jammed one up and subsequent beating apart sent the op to the hospital! And yeah, not having powder in the measure will cause problems too.
For the OP, the good old eyeball, looking inside the case at #2 right before or as you index should solve your problems.
If you PM me your address I’ll send you a KMS UFO light kit for a 550 that will make that a lot easier. Same as the kit on the 550 on the left.