This is what I wrote for a friend when he started using portable electronic scales (the same ones I do):
Loading with electronic scales.
Never trust any scales, electronic or balance. Conditions will change their performance. Therefore, make a test weight for every load you use regularly & mark it so you know which is which. I use old .222 projectiles & trim the soft points with a break blade knife until I have the right weight.
I weigh using the milligram scale option, because 1 milligram is pretty close to 1 kernel of N550, meaning I can load to that precision, all else being equal. I can make you more conversion tables if you need them.
Rules:
Only remove the pan from the scales to dump the load. If you take it off during the loading process, you’ll have to start again because you will likely lose some precision. Scales use what’s called a floating tare facility, which allows them to adjust their tare weight as conditions change, but you don’t want that flexibility to be part of your loading.
Always either measure up to a weight (as you’d normally do), or load down from more than you want – don’t mix. If you drop too much on, take it back under before working to your load.
Force the scales to evaluate every addition you make (even one kernel of N550) by “leaning on” the pan after you add powder. Scales have a bit of “fuzziness” in their precision, which can cause them to translate a small change as a tare correction. Gently touching the pan with something like a flexible spill pf paper will cause the mechanism to positively evaluate every addition.
Give the scales time to settle. On occasion, just one extra kernel can set the load virtually half way between a couple of graduations. Eventually, it will make up its mind & settle on the “correct” value.
Keep away from drafts. These are fine scales & can be influenced by zephyrs, but not as much as some, I’ve noticed.
Procedure:
1. Make a powder shovel. I tear a rose leaf shaped piece of paper out of one of those newsagent cheap paper bags & crease it along the centreline right through the point. That stiffens it up ever so slightly & lets me pick up one kernel, 5, a dozen or whatever to toss in the pan – and scoop out some if I overload it. The paper tears with a fuzzy edge that helps picking up powder.
2. Set up powder thrower to toss just under desired load.
3. Set up scales & check with standard weight & test weight. Add pan and tare scales.
4. Check that scale is reading correctly using your test weight.
5. Throw a charge into a separate container (I use a balance pan from my beam scale) & pour it into the scale pan, making sure that you don’t bump the pan or scales.
6. Lean on the pan with your paper roseleaf, wait & read.
7. Add powder with roseleaf, lean & read until correct reading occurs.
8. Remember to check that the scale has returned to tare zero reading before dumping next charge from measure.
Precautions, hints:
If ever a load acts abnormally, eg doesn’t increase when you add powder, dump it, retare the scales & test with your test weight.
Be careful not to dump powder onto scale balance top. I’ve done it - it’s easy for a kernel to slip past the pan.
Occasionally dump an earlier charge back onto the scales (via your separate container of course). As much as anything, this will reassure you that the scales are accurate & repeatable (or at least mine did).
The negative reading that you see when you take a full pan off the scales can change during the course of a loading session. If you become uncomfortable, tare the scales without a pan, add the pan & tare them again.
Don’t bother to use a trickler. It is a nuisance with powders like N550 which can clump & fall in bunches & besides, when you get practiced with the roseleaf, you’ll be dumping a counted number of kernels on the pan in no time.
Precision with N550 is near enough to 1 milligram most of the time. Precision of AR 2206 is closer to 2 & 2208 would be not much different. Precision is a function of kernel size & weight.
Getting lazy in my old age, so you can edit it for your situation.
John
