ye, realise it's load development, and it's as long as a peach of string, but there is also tribal knowledge, whats has been seen, a powder/primer combination thats known to work, vs a primer/powder that simply don't like each other
I use CCI 250 almost exclusively on my 338LM, 300NM and 300WM and load work up with N570 right at 5SD, 10-11ES and have a friend that uses the 215s on his 300WM and 300PRC and get about the same results with N570. You would be fine with either.
You won’t find that much difference, and certainly not one that points to which your rifles load combination might prefer without testing, if it results in a preference. They are effectively equivalent.
Exactly that - the 215m is a harder cup than the 250.
when you have the anytime/always available of both then the above questions mean nothing, when just finding a primer for Magnum rifles is a issue then knowing the difference and which performance are closer becomes a fact of live.
