MD says they are the same, I do not and one technician from Ramshot said definitely different powders. But they are so close they usually can interchange with allowances for lot to lot variation. My understanding is same base powder but different retardants used, also MRP is more uniform in all ways: lot to lot, grain size, burn rate. I don't know if there is any difference in temperature sensitivity but if there is the slight edge would go to MRP.
Both came from the powder used in 6.5x55 Scandinavian military loads, first with a 156 grain bullet and later a 140 grain.
