Never had any case head separation in any bottle-necked rifle cartridge except some fairly mild loads in a .223 Colt AR - & these were once-fired, in the same rifle.
Full length resized, fairly mild load & who knows? Brass looked great, everything normal.
2X from the same reloading batch & I ended up scrapping the whole deal.
Only good thing was both foward hunks of brass were psuhed out the chamber with w brush on ing rod from the muzzle - at least the range session wasn't lost.
No idea to this day. BTW, Federal American Eagle factory rounds, shot & reloaded ....
Rounds fired normally, & actually, were as accurate as any that didn't separate - working up a loading.
I dunno ....