I talked to a bud whose job is calibration and gaging for Government ammunition plants.
He says that match primer lots are picked out from unusually consistent lots of primers. Workers are given incentive pay if their primer cake is used in the match primers. But, the process of mixing primer cake is such that they cannot assure that each and every mixed lot has the consistency for match primers, it sounds as if extreme consistency is a hit or miss process.
I do know that there are other variables, such as the amount of primer cake in the cup makes a difference in ignition, so there is more to making a good primer and the manufacturer’s are not letting that information out in the public domain.
Most of the real good target shooters I shoot with use CCI Benchrest primers, so either the primers are good, or they are simply buying them because the box is stamped “Benchrest”. A bud of mine who has won National F class championships uses CCI Benchrest, Federal Match, and Russian primers. It all depends on the results of his load testing.
I shot some Russian primers, testing the things, and they shot great.