Continuing Monday education series:
Pistol ammunition, like a handgun has four basic parts. A single round of ammunition for a handgun is called a cartridge (Not a shell: a Shotgun, a mortar, and a battleship take shells which are a different type of ammunition). The cartridge consists of: (1) the projectile. Also known as the bullet this leaves the muzzle end of the barrel at high velocity and does the work of the handgun. (2) the case (sometimes referred to as the brass because that is typically what it's made from. More on that in another post). The case holds all of the components together until the round is fired. Inside the bottom of the case is a small hole called the flash hole. Also within the core of the case, sitting above the flash hole is (3) the powder charge. This is a precisely measured amount of gunpowder. Finally there is the (4) Primer. The primer is a small explosive charge made (usually) of lead styphnate contained in a small zinc container. It is located in the base of the cartridge and can be seen when you turn the round over. The exception to this is so-called "rimfire" ammunition such as .22 LR, .22 Mag., .17HMR, etc.In those rounds, the rim of the case itself contains the lead styphnate charge to prime the powder charge. In the case of rimfire ammunition, the entire base of the case is the primer and it does not matter where on the base the firing pin strikes when the gun is fired. All other handgun ammunition is "center fire" ammunition meaning the primer is a separate component located only in the center of the base of the case. When the firing pin of the firearm strikes the primer of the cartridge, the primer shoots a small charge from the lead styphnate in the form of a spark (or "flash" through the flash hole in the bottom (interior) of the case. This charge then ignites the main gunpowder charge which burns very rapidly. As it burns, gasses quickly expand and look to go somewhere down the path of least resistance. This is the open end of the barrel. As the gasses expand and the pressure builds, they unseat the bullet from the case and propel the bullet out the barrel. The sound you hear when a gun fires (most of it anyway) is actually the sound of the bullet leaving the barrel at supersonic speed. As the bullet breaks the sound barrier the air immediately ahead of it is compressed then suddenly expands as the bullet passes through it much like the tip of a whip cracking because it is accelerated to more than the speed of sound.. (Sonic boom). While not part of an ammunition discussion, in order for "silencers" (actually called suppressors) to truly quiet a shot down (it is never silent) they require slow (sub-sonic) ammunition that does not break the sound barrier. What caliber is my gun ? "Caliber" means the piece of ammunition is a U.S. developed round. "Caliber" is the diameter of the projectile itself measured in 100ths of an inch. Therefore a .38 caliber round has a bullet that measures .38 or 38/100ths of an inch in diameter. A .45 caliber round has a bullet diameter of .45 or 45/100ths of an inch in diameter. When there is a third digit in the "caliber", it reflects a difference in the case design. Therefore, a .380 caliber round is a .38 with a different case. The .30-30, .308, .30-06, etc. all have a bullet that measures 30/100ths of an inch in diameter but very different cases. They are NOT interchangeable ! Who uses the metric system ? Every other country in the world ! That means if you have a 9MM, 10MM, etc. it is a foreign developed round (usually European). This simply refers to the same thing as "caliber", but is the bullet diameter measure in millimeters because those countries use the metric system. Ironically, if you do the mathematical conversion, 9MM equates to 38/100ths of an inch, 10MM equates to 40/100ths of an inch (.40 caliber) etc. Again, that does not mean the rounds are interchangeable...they are NOT ! Extreme caution must be used not to load .380 ammunition into a 9MM. .380 is actually 9MM "short". It will load, cycle, and fire in a 9MM, but because it is not properly fit the the breech end of the barrel, expanding gasses can (and will) escape through other routes that the muzzle. This can cause extreme damage to the gun and personal injury to the shooter !! Every piece of ammunition is stamped on the bottom what kind of round it is. Every modern firearm (extreme caution here with old guns) is required to be stamped on the gun what ammunition it takes. BE SURE THE AMMUNITION MATCHES THE GUN ! Once again, please feel free to ask questions. Next week: Types of pistols and actions.