How much pressure in a charge will a cci 300 primer make verses using a cci 350 primer?
Can i use the cci 350 primer in place of the 300 if i stay at lest a grain or two back from max listed loads in the 45LC and have no pressure signs with the same load useing the 300cci primer allready?

bearhunter,

Your rule of thumb "1 to 2 grain down with the magnum primer" is about right, but each load and gun can be different. So...do it smart - Work up the load again using the magnum primer.

Here is a reason to NOT use a magnum primer with the 45 LC. The very vast majority of powders do not need a magnum primer to ignite AND the use of a magnum primer can kick the bullet forward, before the powder even ignites, out of the crimp and cause inconsistent ignition.

I've tested this with my 45LC using max charges of H110 or Lil'Gun and heavy 285 or 335 gr LBT cast bullets. Accuracy, consistency, ES and SD were all better with standard primers.

Alan