Why do some rounds use magnum primers and others don't?
When I started reloading .40 S&W I was confused why it used a small pistol primer, and not a small pistol magnum primer, it seemed like a magnum round compared to 9mm. The reason is the height of the powder column, .40 S&W is still a fairly short cartridge compared to something like .357 Magnum.
What happens if I accidentally deprime a live primer?
This is something I worried a lot about, I purchased a bunch of used brass from an estate, and as I was sorting the brass by cartridge, I realized there were some primed brass mixed in with the fired brass. While I do think I found all the primed brass, before running the brass through my deprimer, the internet says that I most likely would have been fine if I deprimed live brass.
What is a squib load / what happens if it happens?
Squib load is a round that has little or no powder in the case. The primer/powder isn't enough to cause the bullet to travel completely through the barrel. This happened to me after I moved my press, and didn't have the powder die setup correctly. I immediately realized the round didn't sound right, stopped, and removed the barrel. I used a brass cleaning rod as a punch to remove the lodged bullet. Failure to clear the bullet before firing the next round could cause high pressure in the barrel and lead a damaged barrel, and risk harm to the shooter.