Why must manufacturer's instructions regarding powder types be followed?

Following the manufacturer's instructions regarding powder types is crucial because different firearms are designed to accommodate specific types of powder. Each powder has distinct characteristics, such as burn rate and pressure, which can significantly affect the firearm's performance, safety, and reliability. Using a powder type that is not recommended by the manufacturer can lead to dangerous situations, such as excessive pressure that can damage the firearm or even cause injury to the shooter. This adherence to specified powder types ensures that the firearm operates as intended, maintaining safety and effectiveness during use.