Why is it critical to match the caliber of ammunition with the specifications marked on a firearm?

It is critical to match the caliber of ammunition with the specifications marked on a firearm to ensure proper fit and safety. Each firearm is designed to handle specific sizes and types of ammunition, which include not only the caliber but also the pressure and overall dimensions. Using ammunition that is not specified for a firearm can lead to dangerous situations, such as misfires, excessive pressure, or damage to the firearm, which could result in injury to the shooter or bystanders. Properly matched ammunition allows the firearm to operate within its intended parameters, ensuring reliable performance and maintaining the integrity of the firearm itself.