What type of ammunition must never be used in a firearm?

Using ammunition that is not compatible with a firearm's specifications can result in serious malfunctions or injuries. Each firearm is designed to operate with specific types, calibers, and specifications of ammunition, which are detailed in the firearm's user manual. When ammunition does not match these specifications, it can lead to catastrophic failures, such as chambering issues, excessive pressures, or even explosions. This is particularly critical because improperly matched ammunition can affect the firearm's performance and safety, significantly increasing the risk of accidents.

In contrast, previously fired ammunition is often perfectly safe to use if it has been properly inspected and is compatible with the firearm. Standard factory-made ammunition is manufactured under strict quality controls to ensure safety and reliability, making it suitable for use in firearms designed for that particular caliber. Additionally, the assertion that all types of ammunition are generally safe to use is misleading, as not considering the compatibility and specifications can lead to dangerous situations. Therefore, only ammunition that matches the firearm’s specifications should be used for safe operation.