How many rounds of blank or ball ammunition must be fired to ensure a seal is created after replacing the bolt carrier key?

Firing 3 to 8 rounds of blank or ball ammunition is necessary to ensure a proper seal is created after replacing the bolt carrier key. This procedure helps to confirm that the gas system is functioning correctly and that the bolt is locking up as it should. By firing this specified number of rounds, it allows gas to travel through the gas tube and exert pressure on the bolt carrier, thus seating the key into place properly within the bolt carrier group. This step is crucial for ensuring the reliability of the firearm, as proper sealing prevents gas leaks that could lead to malfunctions during operation.

The choice of firing fewer than three rounds may not provide adequate pressure or time for the key to seat correctly, while firing more than eight rounds is generally unnecessary and could lead to excessive wear or increased heat without providing additional benefits for ensuring the seal. Therefore, firing within this established range—3 to 8 rounds—ensures optimal performance and helps confirm the integrity of the assembly.