Ammo 101- Powder is not the same as primer
Looking at a cartridge from top to bottom your first layer is the bullet. That’s what leaved the gun towards your target when you pull the trigger. (assuming all goes well. J) The next layer is your powder charge. This is the part that actually is quickly ignited by the primer being hit. The very bottom of your cartridge, usually the round shape at the base is your primer. Primers can be ignited by striking the outside of that round shape or right on the inside of the round base, depending on whether or not it’s rim-fire or center-fire ammo.
What happens when you fire a gun is that the firing pin inside the gun hits the rim or center fire. This causes an ignition of the powder inside the casing, which causes the bullet to propel forward towards your target and the casing to expel out the ejection port. This is how the casings end up landing all around, and sometimes even down your shirt. Since the casings have housed the fiery dance between the primer and the powder, they are inevitably hot–thus, the reason why you don’t want them to land down the front of your shirt and nestling. *wink* Don’t worry ladies. I’ve even seen some men do the “hot casing line dance.” It does happen and for the most part you don’t have any control over it with the exception of what kind of clothing, hat, and eye protection you wear to inhibit the rogue piece of hot brass.