An accidental double load is about the only thing that could KB a gun. A good progressive press will go a long way in eliminating that. Using a bulky powder will also help because if you double charge, it will overflow and you'll easily see the mistake. Powers like Bullseye are less bulky and it's harder to catch a double load. A progressive press makes it pretty difficult to double charge. In order to double charge a case, you would have to pull the handle again without advancing the shall plate and inserting a new case. This action would de-prime a live primer, which can and will set off the primer, which isn't end of the world, but it's enough to get your attention.