Ok. I meant your factory ammo could be steel cased. I took it for granted that your reloads were brass.All my reloads are brass cases, S&B, Hornady, PMC, Norma and Fiocchi. This has not been an issue with Hornady brass as the primer pocket uses Small Rifle.
Since all your factory ammo was brass. I'm going to eat crow and agree with @South Prairie Jim .
I have several rifles that will not reliably fire Magnum primers. They are reliable with standard primers except Fiocchi.