As limpetmine said, the burn rate of the powder is key to proper timing. When you get a modern, faster-burning powder in a semi designed for a slower burn rate, movement of the parts gets out of time. That's when you end up with bent Op Rods. There is modern ammo made to this spec and the designation is ".30-06 Springfield."

Some have had success with adjustable gas plugs. The technique with these is to open up the plug fully so the action won't cycle and then fire and step it back downward until it JUST cycles. The plugs vents off excess gas preventing damage. I've never done it.

Bob