Testing the most accurate Powder Thrower

Dean2

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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 (first slide half open) and then the first slide (smallest slide) for fine tunning, 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 betwween 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, except the occaisional 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.
 
Actually on a given date a certain volume will have a corresponding weight. On subsequent days, if the powder has slightly more or less moisture content due to humidity in the air, then the weight of the same volume will be correspondingly higher or lower. In the same can of powder, the only thing that can change the weight at a specific volume is moisture content or the relative amount it is compacted into that space. This is why you don't want to leave the powder measure opening exposed to the powder while you are doing other things as vibration can cause more powder to settle into the cavity. You want to expose and empty the charge opening on each stroke and leave it facing in the empty position, till the next stroke.


The theory that volume is as or more important than weight comes from the writings of many of the best Benchrest shooters, most of whom load to clicks, as opposed to a weight.

As I said above, I never adjust my measures once they are set, but I live where it is very dry and do not see any weight change in the same can of powder over many loading sessions. The humidity effect is something I have read about, but never seen. The issue with compacting is easy to replicate and I have seen it in action.
 
The theory that volume is as or more important than weight comes from the writings of many of the best Benchrest shooters, most of whom load to clicks, as opposed to a weight.

Exactly.

But if one is using weight to check consistancy in his measure, then he is not measuring by true volume.

Look at it this way-: if you throw a charge and check weight, or trickle up, to be consistant, you're loading by weight.
If ya throw a charge, and ignore the fact that it is .1 or .2 grains different than others in the batch, that's loading by volume.

We've gotten so wrapped up in charge weight, that this concept is tough to get through sometime.

Not saying I agree or disagree, although I have one load in a 223WSSM where my thrown charges (Harrel measure) will consistantly outperform my weighed ones. Now this is with ball powder, mind you, not a coarse extruded. I have actually loaded some (weighed and thrown to compare) in 7wsm long-range load with IMR4831, but haven't tested it yet.
 
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