The Competition Model BR-30 Powder Measure is truly a competition model with some very special features. One of these features (the drum and micrometer) limits the overall charging range from a low of 10 grains (dependent upon powder density) to a maximum of approximately 50 grains.
If you are a serious competitive shooter and your loading requirements are generally between 10 and 50 grains, this is certainly the measure to choose.
This measure uses all of the competition proven features of the Match-Grade Model 3BR. To acheive the most uniform powder metering possible for Benchrest Competition, at a targeted charge weight of approximately 30 grains, (hence the name BR-30) an entirely new drum and metering unit was created. The diameter of the metering cavity was reduced and the metering plunger was given a unique hemespherical or "cup" shape. This shape creates a powder cavity that resembles the bottom of a test tube to alleviate irregular powder settling and to enhance charge to charge uniformity.
A special operating handle was also created for this model. It's a rotating handle, slightly heavier to help you maintain a more uniform stroke.
Big Book Catalog, Issue:68, Page:538
Sinclair, Issue:5B, Page:083