What is a common consequence of using improperly sized ammunition in a firearm?

Using improperly sized ammunition in a firearm can lead to a range of serious issues, primarily related to safety and functionality. When ammunition does not match the specifications of the firearm, it can cause the firearm to misfire or malfunction. This occurs because the cartridge may not fit properly in the chamber, leading to difficulties during feeding, firing, or ejecting. A misfit can result in jamming or even cause the firearm to malfunction in a way that could potentially harm the shooter or bystanders. Thus, ensuring that the ammunition is the correct size for the firearm is essential for safe and reliable operation.