Powder Measure Accuracy

[ELR LVR]

I would definitely be concerned using charge weight differences of a full grain
You are correct in that 1 grain over may put the charge into the unsafe zone
Also with a smaller case such as .223 think of the differences in "percentage of difference"
Such as if throwing 25 grain and you are 0.2 grains over that is a .008% diff
Whereas with a 60 grain case if you throw 0.2 grains over that is only a .003% diff.
So with a smaller case a slight difference in charge weight is actually a larger difference
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I would not be very concerned if you are throwing differences of 0.1 grain
But if you are anywhere near max levels I would not want to vary much more than that
If you are looking for accuracy....I also would not want to vary much more than 1/10th grn.
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If you are merely shooting to hear it go bang and pop cans or whatever
I would choose a middle of the road medium load and not worry about differences of up to 3/10 grn
Ball powders like W748, H335, BL-C2, AA2520 are great as they flow easy and help to reduce variance
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Make sure you put a good amount of powder into your powder measure hopper canister
as the weight of the powder column pushing down on the rest of the powder below it
helps to smooth out flow and reduce variances, similar to how the weight of the air in the atmosphere
pushes down against all the air beneath it.
When you get low on powder in your powder measure, top it off again as you will start to see your
charge weights go down in weight with every throw once the hopper runs low

 

[Mark611]

Good info here! I have also had the same issues using an auto powder dispenser, I have a RCBS Lite, and it is not as consistent as I would like to see it, the +_ .001 it's supposed to throw deviates sometimes more than that or under, even with ball powder, extruded powder forget it! I back up all my charges on my A&D HR-100AZ lab scale to make sure their safe! and if my weights are not in a Tenth of my intended charge weight, I dump them back in the hopper and try again! This is trying to load 26gn of TAC in A 223/556 case, but IMO it's still faster than throwing them all the old fashion way, if I want them with in the 400TH of a grain like I do for my precision loads for my bolt guns I throw them all and trickle them up YMMV

 

[hoz53]

Good info here! I have also had the same issues using an auto powder dispenser, I have a RCBS Lite, and it is not as consistent as I would like to see it, the +_ .001 it's supposed to throw deviates sometimes more than that or under, even with ball powder, extruded powder forget it! I back up all my charges on my A&D HR-100AZ lab scale to make sure their safe! and if my weights are not in a Tenth of my intended charge weight, I dump them back in the hopper and try again! This is trying to load 26gn of TAC in A 223/556 case, but IMO it's still faster than throwing them all the old fashion way, if I want them with in the 400TH of a grain like I do for my precision loads for my bolt guns I throw them all and trickle them up YMMV

thread from 2021 but stll good info

 

[fkimble@charter.net]

As mentioned, with the Lyman 55, you want the cavity deep, not wide. You also want the 3 slides to be even inside the cavity. And for the fellow using 4350 in his 223, that is a much too slow of powder for a 223. Maybe with very heavy bullets. 4350 with its long kernels is also among the worst for trying to throw in a mechanical measure. There is also a SC(short cut) 4350 which is a little better powder for throwing. And 4064 is a measure each charge powder due to kernal size.

Frank