I use a full length sizing die, but make sure I don't push the shoulder back by properly adjusting it in the press. I then check for function and feed of loaded ammo.
: Most belted magnum rounds are oversized in typical cheap production sizing dies, whether Hornady, RCBS, Lee or Lyman. If the shell holder touches the bottom of the die, depending on which way the moon is phasing, the shoulder can be pushed back up to .030". This creates excessive slop of the ctg. in the chamber and results in only 2 to 4 shots per case before the case splits ahead of the belt. This excessive slop is transalated as excessive headspace. Yes, I know belted cases are supposed to headspace on the belts. Have you ever measured any? The headspace in factory rifles is from "0" to + .006" for rimless ctgs. This is the SAAMI allowable limit. Belted magnum brass itself can be out up to .010" and if the gun is out as well .006"?(and it will be)
; Any time your brass splits ahead of the belt, or above the rim or extractor groove, it was due to excessive headspace - there is no other cause, period! The excessive headspace may be in the rifle, or in the ammo, caused by you or whoever loaded it.
: If your brass is not lasting 15 shots, you are ruining it through over sizing OR, loading to excessive pressure and expanding the primer pockets. Excessive pressure does not cause head separation on the brass. Oversizing is not necessary, for any ammo. When you oversize, you create excessive headspace on the shoulder and brass life suffers.
: Some case designs overstretch when firing, and they will have shorter case life. Modern rounds don't suffer from this. My .375H&H brass went over 20 loadings at factory ballistic levels - no more is needed.