Before revision: Historically the first type of autofrettage avant la lettre was mandrelling bronze gun barrels, invented and patented in 1869 by Samuel B.
After revision: Early in the history of artillery people observed that after firing a small number of rounds bore of a new gun slightly enlarges and URLHistorically the first type of autofrettage avant la lettre was mandrelling bronze gun barrels, invented and patented in 1869 by Samuel B.