True, they may have switched to hardened valve seats and valves because it was thought they were needed with unleaded gas but the reason why the valves burnt before was because of carbon build up from the leaded gas. Used to be you took a head off and you couldn't see the valves for carbon. A piece gets stuck under the valve and the burning process begins. Today you pull a head off and you virtually see no carbon build up and that's why there are less valve grinds today, not so much because they changed the seats but because they got rid of most of the carbon. The change of seats and valves was done because it was "speculated " that it was necessary with unleaded gas but you put a piece of carbon under one of these valves as well and it will burn. But either way, the technology and material in engines today is better and that is a plus.
And yes the change should have been sooner. But this is getting way off topic from steel shot and if it affects older barrels. It is obvious today that technology and materials in guns is better today. However when blackpowder went by the wayside, everyone was told not to use the "new smokeless" powder in their black powder shotguns as they would probably blow apart. Yet thousands if not millions of people did so simply because they couldn't afford another gun. Then when modern loads came out it was said not to use these loads in early smokeless guns as it would destroy them, yet again thousands did and are still doing so. Sure there were guns that blew apart but some of these guns had probably been neglected for years and were destroyed from neglect rather than type of load used. I have seen guns only a few years old that I would be afraid to shoot. So now steel shot is the latest advancement as to why older guns should not be used but I do know many who are using their old guns with it. It may sound like I am promoting steel shot in older guns but actuallty I don't use it in any of mine. I am just trying to seperate speculation from reality. But really when you think of it, unless a gun is a valuable collector piece, does it matter if the steel scores the barrel after a period of time because what good is the gun sitting in the corner collecting dust. And if it takes some time to damage a barrel, that could mean quite a few years for the average hunting gun.
