Does not matter if you are loading for a magazine gun. Just start at max COAL for the magazine and work backwards. Too many people get tied up trying to make BR rounds for a mag gun that will not load in magazine.
Second the thread above about chamber and extract the round giving you the COAL...
there have been more than one powder recall. One of the most infamous was a super hot batch of RL 22 out. I had to drop a whole 5 grains in a 6.506 AI to keep from blowing sears and triggers. Either buy enough of same lot or drop 10% and retune.