I keep all my powder, primers, and bullets on the shelf on the wall BEHIND me. The ONLY primer box on the bench is the same type as the primers that are in the loader. The ONLY powder can on the bench is the same powder that's in the machine. The ONLY bullets on the bench are the ones I'm loading for that particular round.

Do this religiously and you won't encounter "sudden rifle disassembly syndrome" at the range or woods.