FWIW, .4 gr. increments give a decent spread, lower the number of loads tested (e.g. 6 across a two-grain spread), and for OCD types are tidy (e.g. 43, 43.4, 43.8, 44.2, 44.6, 45). To minimize variation I color-code each load with sharpies, mag-load them in order, and fire all 6 loads. I wait 10...