Loading with 215's over 210's

[Cossack]

According to an article in a gun rag that skips my 67 yr old mind, some mag primers are actually less "hot" than standard primers of another brand. And "benchrest primers" are only standard primers that are made by the most consistent primer maker.
Yes, you can use mags, just cut back 3-5% and work up the load....as you would do if you change ANY reloading component.