The factories I've visited over the years have used some variation on a drum measure, if I recall correctly. (Some of the visits were more than 20 years ago!) In genera, they also don't use the large-granule extruded powders so many handloaders--older ones in particular--are so attached too.
Another thing the factories do that many handloaders don't is run extensive tests on velocity consistency. They also understand that the standard deviation from a 3-5 chronograph string is statistically useless--as are one or two 3-shot groups. Instead they'll often run SD's and group-tests on several dozen shots with a certain load before settling on the final powder charge for THAT lot of powder.
