I had 7mm RM by Nosler brass split 3necks out of 20 on a mild load used specifically to gently expand cases , as the virgin brass was quite short on headspace. I annealed the next batch of virgin before use , and all 30 remaining gave me no problems. I’ve got Norma 7mm brass going on 10 reloads ( using Larry Willis collet die). Also, the Norma brass sizes up very consistently. Your friend needs a friend with belted mag reloading experience. Best of luck