Architect Louis Sullivan coined the term "Form follows function", and that seems to apply to a lot of these old tools. The elegant simplicity of Gil's tools illustrates that you don't need either a $1200.00 progressive loading press or expensive factory loads to feed our vintage doubles with appropriate loads. Speed is nice sometimes, but it isn't really necessary to produce enough quality shells for a season of bird hunting.
Miller, the charge tubes for the Belding & Mull Measures are indeed adjustable and volumetric. You set them for the desired charge, and the measure fills them. Then they are removed and dumped into the shell. Lather, rinse, repeat. The reason the B&M was so consistent is that the design incorporates two vessels or hoppers for powder. The brass upper hopper will naturally vary in depth and volume as you fill it, and gradually use it up. But with the B&M, the lower chamber with the little glass window fills up to the same level every time you pull the handle, and the next charge is taken from there, with no influence from the varying amount in the upper hopper. For bench rest and target shooters, consistent volume is more important than consistent weight, because the same charge can vary in weight by 1 or more percent just from the moisture content of the powder, due to changes in humidity. B&M made different charge tubes with small volumes for pistols and different larger sizes for larger rifle charges.
I've used a Lyman No.55 Powder Measure for years, and find it to be very consistent so long as I top off the hopper when it is drawn down about half way. And my Dad taught me to always use the same force and speed to operate the handle, and to make a habit of flipping my finger on the little knocker after each and every drop to knock loose any powder granules that might bridge or get stuck in the measure. Again, form follows function, and that little knocker that the competition chose to leave off their measures is something that makes the Lyman No.55 as good today as it was when it was introduced. As Miller says, basically the same design has worked well since the 1800's. Any problems with these simple tools can usually be traced to the guy who is using them.
