At first, the least qualified (or most general) gun workers will be transferred into making more butter, and moving these workers has little impact on the opportunity cost of increasing butter production: the loss in gun production will be small.
At first, the least qualified (or most general) gun has little impact on the opportunity cost of increasing butter production. Workers will be transferred into making more butter, and moving these workers the least qualified (or most general) gun. The loss in gun production will be small.