I have a Pact Unit and a buddy has the RCBS Charge Master. I have no
experience with the Lyman unit.
I would say both are similar and both are accurate. IMO, they are both
slow. But they are very, very handy is when you are working up loads;
and you are increasing powder charges by 2-3 tenths of a grain at a time.
I use the Audette ladder method of working up loads. My powder throw
is accurate to +/- 0.1 for my rifle charges and that is good enough once
I have a proper load worked up.
I will add that line power coming in can have a marked and noticeable
effect on the scales performance. I purchased a power filter that you
would use with an entertainment center. It really improved the
performance of my scales. I used to have drift and at times erratic
readings with static masses. I finally figured out it was the line power
variations. The power filter solved all those problems.
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An Unarmed man is a Subject. -- Unknown
"I am prepared are you?" -- Shade
"Regulation, registration, confiscation, domination, that's the Progressive agenda." -- RED Caddy