Be careful about ammunition that has been loaded and reloaded into magazines and chambers. Bullet setback can be dangerous.
When a round is chambered, the cartridge’s bullet sometimes hits the feed ramp or other parts inside the gun. Repeated use can push the bullet further into the casing. For example, you unload your semi-automatic pistol for some dry-fire practice. Then you reload it with your everyday carry ammunition when you are done.
When a round is chambered again and again, the cartridge’s bullet hits the feed ramp or other parts inside the gun, pushing the bullet further into the casing. This can be caused by repeatedly unloading and loading your firearm. For example, you unload your semi-automatic pistol for some dry-fire practice. Then you reload it with your everyday carry (EDC) ammunition when you are done. A little bullet setback may not be noticeable or a big deal, but look at the comparisons in the images below. You can see that this ammunition may be past the safe pressure limits they designed it for.
If you are not careful, the cartridge’s overall length, or C.O.A.L., will shorten with use. As the bullet pushes further into the casing, the internal area decreases. When the gun is fired, that smaller area can increase pressure when the gunpowder is ignited. Suppose the internal pressure exceeds the safe limit for the cartridge. In that case, the ammunition could damage the weapon when fired or, worse yet, injure you. As a result, you risk destroying the weapon or having a malfunction that you cannot clear by hand. You definitely do not want that when it is time to use your gun.
Another example of what causes setback is when someone gets home and unloads their gun each evening for “safety” around the house. They load their gun and chamber a round the next day before leaving for work, setting the stage for bullet setback. Instead, they could leave their gun loaded and securely put away each night. Many safes or locking cases are available that will still give you quick access to your firearm when needed.
The solution is simple: stop chambering the same round over and over. Each time you train or clean your gun, cycle the round that was in the chamber to the bottom of the magazine. This may not completely prevent a problem over a long period of time, but it can help reduce the chances of you having problems. It is also a good idea to occasionally shoot the ammunition you carry to see how it performs compared to what you practice with. That's the perfect opportunity to replace what has been in your gun.
Bullet setback is something to be aware of and watch for. Handling your firearm safely by adhering to the four safety rules is just part of carefully caring for your weapon and its ammunition. If you find a bullet with an excessive setback, put it to the side and properly dispose of it.
Brian Armstrong grew up in a small farm town in rural Indiana and learned to shoot before he learned to drive. His career began as a firefighter and medic in Ft Wayne, IN. Throughout the years, he has owned multiple businesses, from construction to technology. His life has come full circle, and he is back to his emergency services roots, teaching emergency first aid and firearms courses.
Brian believes that the best way to learn “HOW” to do something is to first answer “WHY” you do something. He is an average guy with views like yours and is now sharing the knowledge gained from teaching, learning from others, and researching the topics you don’t have time to explore. Follow him at @LetsTalkDGU
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