IMO, let's say you are starting with a game gun in good condition, locks up tight and no loose ribs etc. If you shoot 7/8's loads and as someone mentioned clean the action especially behind the ejectors or extractors and the hook there is no reason to think the gun won't outlast you. I have had a Dickson boxlock and WJ Jeffery sidelock that I put 5-7000 light rounds through every year I owned them and they showed no sign of wear. The Jeffery was made 1906.