is the scale on the rcbs nota accurate to .1 grain? I saw a video of a guy doing what you said. set it a bit low and trickle a bit after. i thought this would be good for that.
The scale on the RCBS is statically accurate, that is it always reads the check weight when I put a check weight on it. The issue is with the dynamics of weighing while powder is falling on it. The powder is scrolled out of the tube and can clump, more with some powders than with others. The scale can't retreat, that is it can't remove powder to get an accurate weight, it can only add and then try to stop at the right time. The clumping can result in it going over.
The other part of it is settling time - the digital electronics need to sample the scale weight free of any dynamic effects from the powder dtopping on it. You can see the software trying to wait for the scale to settle before weighing as it approaches the correct weight.
The dispenser is more accurate/consistant with ball powders like W760 and AA2460 than it is with stick powders like IMR4350 and IMR7828 which is a bit dissapointing but completely understandable. It's dissapointing because the stick powders are the ones you would most like to have it work the best weith since they don't work well in normal powder measures. The ball powders work fine in normal manual powder measures.
All that said, as a premeasure the ChargeMaster is a very very good tool. It adjusts to a new charge as fast as you can punch in the numbers which makes it great for loading test ammo in .2 or .5 grain increments, an arduous task otherwise.
All that said, I like the ChargeMaster. I use it all the time. I'd buy mine again knowing what I know now, but I don't use it to measure powder and blindly dump it in the case with out running it over a beam scale or a lab grade digital scale first.
Fitch
