I personally only use data backed by a test barrel.One example being Rick Jaimeson's testing the .450 Marlin with bullet's not used by the factory loadings,then shot thru the .450 Guide Gun.Know guessing because he took the work out of it useing both and chronographing both.
Even at 40,000 CUP there is a safety factor built in.Some load to the mid 40's and sell it and havn't been to court yet for it.Other's publish it over the internet(responsible sites).Some have tested the action and claim it's good to 50,000 and Marlin is making the .475 Linebaugh listed at 55,000 PSI in the same action.Who know's?
I will stick with 40,000 just for Hunting loads and leave the guessing to those that really know.
Best of luck.
