Does anyone have a source for cartridge headspace gauges for 416 Rigby and 470 NE? I just got a copy of the Art Alphin book, and he suggests that simply dropping the die down to the shell holder may give excessive shoulder pushback.. I've reloaded for 25 years, and silly me, I've always just followed directions that came with the dies. Maybe it's time to modify.
I have looked at Midway, Grafs, Brownells and Huntington's, and haven't found these for sale.

If you have a double rifle with excessive headspace in 470 NE what are you going to do?

Good question. It's just that reading this has cast an element of doubt on my loading practice, and at least if I had a cartridge headspace gauge I would be certain I was at least within SAAMI spec.