When forming brass(45super) for 400 corbon I use accurate arms data for the 155gr xtp...11.1-12.3 of no.7 start to max with a cci 350 primer(usually use mid range). These numbers work with cci 300 primers also from what I've read. The problem is when I use 400 corbon brass with small pistol or small rifle primers, the data from Corbon calls for a start of 12.6-14.0 of no.7. Question is do I feel safe starting at 12.6gr with the small primers when its .3gr. over max with LP primers? I guess I'll start at 12.3gr and see what happens and work higher if needed. Is there really that much difference in pressure between the large and small primers?