Bat in The Armory shows how a KWA gas blowback B&T MP9 is upgraded into a full-metal airsoft replica, a project costing over $1,000 (or €) in parts. The comprehensive process covers everything from systematic disassembly of the MP9, including its attachments and internal components, to the replacement of key parts with VTEC full-metal upgrades. These upgrades range from a longer inner barrel and a new hop-up unit to an entirely new full-metal bolt system, trigger system, and various reinforced internal components like the hammer and disconnector.

From there, he goes through the careful reassembly, emphasizing proper greasing of metal parts and correct installation of all new components. After the internal transformation, all external attachments are reinstalled, completing the build. A thorough cost breakdown is provided, detailing the total investment including the base MP9, magazines, and all upgrade parts.