I had a wierd happening several months ago with my Dillon 550. One case got a half load and the next case got a load and a half. Turned out a small piece of stryafoam was in the powder, (I think from the seal on the powder container), jammed up temporarily in the drop tube and only dropped a half load then came loose and dropped the other half, plus a full load. I noticed power was almost to the top of the case and stopped before I put a bullet in. Found the piece of stryafoam in the over full case. Pulled the bullet in the prior case and found it had only received a partial charge. One could have caused detonation, or at least a squb. the other could have also a caused a kaboom. All because of a piece of scrap stryafoam. Not the fault of the Dillon powder measure. It has always been accurate to +- .1 gr.