I try to employ some simple safety rules when hand loading to keep the “uh-oh” factor off my reloading bench as much as possible. One of the simplest and most effective is my self-imposed rule to try to use a powder that loads 50%+ of the case volume prior to seating the bullet.
Why?
1. I always visually check each case to make sure that I can see the powder inside. If the amount of powder that I’m dropping is only filling 25% of the case, let’s say, then it can make it difficult to get the correct angle to see the powder inside the case, especially if it is a tall and thin cartridge like a .357 Magnum or a bottle-necked rifle cartridge.
2. If I should accidentally double charge the case, and I’m filling it with 50%+ of powder for a normal loading, then a double charge is going to spill powder all over the place and make me use bad words. Trust me, I’d rather spend an extra ten minutes cleaning up a mess of spilled powder than going to the hospital because I failed to notice a double charge. If my normal loads only fill 25% of the case, then a double load could easily go unnoticed and won’t even give me a crunch when I seat the bullet in the brass– that is not good.
3. Not safety related, but worth noting anyway: the way powder lays in a cartridge case will affect how it fires the projectile upon ignition. For instance, if a case is only 25% full and the powder is all piled at the rear of the case when it ignites, that will deliver a different velocity than a cartridge that is ignited with all the powder piled at the front of the case. The best solution to this last problem? If the case was half full prior to seating the bullet, the volume will be more than half full with the bullet taking up some of that case volume, so the likelihood of excessive air gaps existing will be reduced.
Really, the most important takeaway here should be: if at all possible, load to 50%+ case volume so that an accidental double charge will make such a giant mess in the middle of your reloading machine, it will be impossible for you to miss it.
