I see no problems with those spreads. To get tighter tolerances you would have to weigh each bullet, trim all matching head stamp brass to the same length, and hand weigh each load. But that would take way to much time for the marginal increase in accuracy. What I do is I'll dial in a charge weight, cycle about 10 charges while dumping them back into the powder hopper, then load 13 rounds for each weight of powder in testing. I load 13 so I can drop 2 extreme variences and have an extra for just in case.