A couple of summers back I bought a Neil Jones Precision Powder Measure. It is a very precise and expensive measure that will throw H4350 to +/- a tenth of a grain when it doesn't hit the mark exactly -which is most of the time. Lets just say it is accurate enough to make me dispense with trickling unless I happen to take up 1000 yard comps at some future date.
The big thing with the Jones measure is that the maker claims they are so precisely built that any two Jones measures, anywhere, would throw the exact same charges with the same powder if the vernier was set to the same setting on both. This is a pretty stout claim but folks on line attest to being able to call a friend and relay a powder charge as "40 clicks on a Jones..." and be assured that the guy on the other end will get the exact same load with discrepancies accountable to variances in lots of the same powder.
Today I got to test this. A friend bought a brand new Jones measure and brought it by for a comparison. Using randomly chosen settings on the vernier we measured IMR 4895. The results weren't good. We got a three grain variance, for the most part with his throwing light. We used a ridiculously small charge to start : 17.5 grains as that would be difficult to meter. My measure threw the charge to an exactitude. His was +/- a half grain and light by those three grains. We finally got frustrated and took his measure apart. We found that oil from machining had cause a bunch of powder to stick onto the inside of the powder chamber. We cleaned it with alcohol, dried it, and they lightly lubed it with powdered graphite per instructions. This changed things dramatically! With all charges, 17.5, 23.5, 35, and 41.5 grains (the latter being our favorite 308 target load) the measures threw exactly the same charges within the variance for that powder. If not exactly at the chosen mark, the loads were inside .1 grains either way. It was pretty amazing.
So. If you want an unbelievably accurate and repeatable measure, look this guy up.~Muir
Neil Jones Custom Products