If you anneal the top third of the case before loading and fireforming, you'll likely reduce the case splitting problem to near zero.
maybe just the particular lots i was dealing with, but R-P cases split quite a bit if not annealed...i had fewer problems with Federal or WW.
formed about 200 pcs of WW into 30/30 ackleys last year, had only 3-4 per hundred split when using virgin cases; dont think any of them split after i had annealed them.
i also neck them to .25 & 6.5, those split a bit more often when i didn't anneal before making .25x30/30ackley or 6.5x30/30ackley.
