This must be about ?? times this question has popped up, and same for the answer.The nice lady on the phone replied that they were identical and that CCI's own employees bought only the SR primers for both purposes because they were priced slightly lower. She even took the time to double-check on her computer to confirm they used the same cups and anvils and had the same quantity of priming composition in them.
One reason I prefer to stockpile CCI primers, especially SR/SP standard and magnum. Before the covid monster appeared, I decided to restock my SR inventory as my five .223/5.56's, and a pair of .300 Ham'rs all shoot just fine with CCI's. For some reason, (the possibility that Don might lose, mainly), I went for 5K of each, standard and magnum. I have lots of primers. Thanks Unclenick