Trying to poll and see what primers have worked best in this cartridge? Magnum or non along with coal in this little wonder? I'm far from being new too reloading as finding out with a variety cartridges and powder combos that it doesn't matter what the book states! This will be in an AR10 with no more than 2.830ish" depending on the mag used and is why such a shot round for what it's design is. Until it's built all is unknown?