Back in 05 or 06, I tried weighing charges with a Harrel, a RCBS BR model, a Hornady BR and a Lyman 55. I test threw individual loads, then groups of 5 throws weighed together, and then groups of ten throws. I repeated this with two of my more commonly used powders, 23.4 of Benchmark and 12.6 of Lil'Gun.
The Harrel's single biggest advantage is you can reset the volume exactly, every time by just counting the clicks. In fact there is an argument that volume is what you should load by and the weight changing due to humidity etc should be ignored.
The most accurate, in terms of lowest deviation was the Lyman, much to my surprise. Set up properly using the 1st and 2nd slide for setting close (2nd slide half open) and then the first slide (smallest slide) for fine tuning, it would throw the 5 and ten lot groups at exactly 5 and ten times the nominal weight. On individual loads its max deviation was 1/10, being half a tenth over or under, and the SD was less than half that as 80% of throws were spot on.
The Harrel's was close but only about 60% of its throws were spot on and the deviation was from 2/10s under to 1/10s over, so quite a lot larger SD. The RCBS and Hornady were about half of that result.
One thing I clearly learned in this test, with all of the throwers, was that a consistent stroke and operation were key to consistent charges, as was ensuring the cavity was in the down position until the actual charge stroke was made. This kept the powder from settling in and packing into the cavity if I took longer to do something between charge strokes.
I sold my other measures and now have a number of lyman, all set to specific charges and powders, with one spare for adjusting for the loads I don't shoot as much of, like my big game hunting rifles.
The Harrel Culvers are great and smooth powder throwers and the Culver adjustment is very handy but for pure accuracy I will stick to the Lyman. I now no longer weigh any charges with short grain powders, except the occasional check charge just because it makes me feel better. In the 4 years since I have gone to this system, I have never had a preset one move and I don't adjust them for the humidity effect that can change the nominal weight by volume by 1/10 either way on any given day.
No thrower throws large grain powder like 4895 very accurately, you will always have to throw 1-2 tenths light then trickle them, but spherical or short grain powder like 8208, benchmark etc are very accurate. Also, throwing close with a Lyman is a lot faster than hand throwing, even if you have to trickle the last tenth of a grain.
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