I have the Redding 3BR. I have been EXTREMELY impressed with this measurer. It will not have any variation at all with any ball or flake powder. With stick powder, it can vary by .1 grain. I still consider this to be extremely accurate.
Here are the benefits of this measurer:
1. This measurer comes with a baffle, which is a must for any accurate measurer. The purpose of the baffle is to settle the powder near the hopper consistantly, no matter how much powder is in the tube.
2. It comes with a universal micrometer. I have used it to throw charges from 4 to 68 grains with next to no variations, except with stick powders as noted above.
3. There is a set screw on the side of the measurer. After you set your micrometer, you tighten the lock. It locks in the micrometer and doesn't let it move. This guarantees you that you will have the most consistant, repeatable throws of any measurer out there.
The measurer doesn't really need any accessories, but Redding does have some available for it. If you are going to load alot of low weight handgun charges, you can get their handgun metering chamber. It will allow greater detail if using 0-10 grains of powder, but I have used mine with the universal chamber down to 4 grains and still remained consistant.
I am extremely happy with this measurer. If I had to do it all over again, I don't think I would go with a more expensive measurer. This one does it all, and I couldn't ask for more.
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=759813&t=11082005