From the US Liberty Ships that supplied Britain during World War II to major airliner disasters, large caliber guns and hypersonic wind tunnels, residual stresses have both created catastrophes and improved safety. Taming and using residual stress effects is now a necessity. Tony will outline the background, focusing upon the development of pressure vessel design between the 1960s and today. The large caliber gun routinely operates closer to its fatigue limits than any other device. Tony will describe how beneficial residual stresses are created within gun barrels and civil pressure vessels via ‘autofrettage’. These permit order-of-magnitude improvements in lifetime whilst achieving ‘fail-safe’ behavior. This has required close collaboration between materials scientists and engineers over several decades.Finally the remaining ‘known-unknown’ (accurate modelling of swage autofrettage) will be addressed.