I won't deny that this powder is finicky but when you get it right it is very accurate with more pleasant blast and recoil than some magnum powders. My most accurate load in the 454 is a mildly compressed load of 4227 under a Cast Performance 335 WLNGC. What I have found is that lighter bullets, lighter loads and lighter crimps will cause the partly burned granules to appear. When the load is right the granules go away and accuracy appears

Don't give up on it for the 500 Max too quickly - it would be the first powder that I'd try for such a big case.