Monday Continuing Education Series
When purchasing ammunition for your firearm what is most important is to buy the proper ammunition for your firearm ! Does your .45 caliber pistol shoot .45ACP, .45 AP, .45 LC, or .45 GAP ? What about your trusty 9mm ? Does it shoot 9mm Luger, 9mm parabellum, 9x18, 9x19 ? In some cases (.45 AP/.45 ACP, Luger and parabellum for example) they are interchangeable, in other cases they are not. This has to do with something called "head spacing" and deals with the pressures that build inside the chamber when fired. The real problem lies in the fact that often these different rounds may chamber and fire in your pistol but may well blow it apart if the chamber pressures are too high. for example, a .380 cartridge will load and fire in a 9mm, but the head spacing is incorrect and it can damage the pistol (or worse, the shooter !).
An AR in 5.56 mm will safely shoot .223 ammunition, but a .223 will not safely fire 5.56mm. Be very careful here ! 5.56 cases will seat in a .223. In this example it's not the head spacing but the case wall thickness that builds additional pressure. Much like the previous comment about ARs, the .357 magnum will shoot .38 special ammunition but a .38 special will not shoot .357 magnum. Once again, it has to do with the chamber pressures and the much more powerful .357 magnum is built to handle more pressure than .38 special creates. The opposite is not true. Luckily, manufactures were smart enough to design your modern pistol so that the cylinder of a .38 special will not close with .357 magnum loads in it. Then there's .38 Auto,, and .357 Sig ! .32 Spl, and .32 AP ! These are "specialty" rounds that are NOT interchangeable ! It's all very confusing to a beginner. Fortunately there is a simple solution ! Every modern firearm is required by law to have stamped on the barrel or receiver exactly what ammunition it requires. Simply make sure the stamp on your firearm matches exactly what is printed on the box of ammunition and you're good to go. This is not the time to listen to cousin Earl who may or may not know what he's talking about ! Be especially cautious when he states, "Don't worry, I do it all the time !" To confuse things a little further, ammunition also comes in +P and even +P+ in the same caliber as the stamp on the firearm. In this case. The 'stamp' may or may not say +P rated. Here it is VERY important to read the owner's manual to determine if your pistol is designed to handle the increased chamber pressures of these loads. It may not be part of the receiver / barrel stamp information on caliber. Unlike your new car (where you threw the manual in the glove box and only refer to it when you need to find the fuse box), it is CRITICAL that you read carefully your owner's manual. Remember when I said "Modern" firearms are stamped ? What do you do with granddad's hand-me-down pistol that is so old it is not marked ? In this case it would be best to take the pistol to a qualified gunsmith. Not only will he be able to tell you what ammunition it takes, but it is also a good idea to have the pistol inspected to make sure it's safe to fire. By now, you've read (hopefully) enough of these posts to know I always end with, "If you have any questions please feel free to ask." Asking might save you from severe injury !