How critical is measuring powder to .01 grains

MKWas said:
Accuracy vs Precision. In metrology the two terms mean very different things. It is important to know both.

Accuracy is how close a measurement is to the real value. If you have a 100 grain weight does your scale actually read 100 grains? since there is some variation you need to take multiple readings & average. A scale that measures 100 3 times is as accurate as one that measures 90, 100, 110. One that measures 110 3 times is less accurate than the other two. For a first pass, a scale that measures to 0.01 gr is 10 times as accurate as one that measures to .01 gr. Maybe!

Precision is how close repeated measurements are. For the examples above: the one that measures 100 3 times & the one that measures 110 3 times have the same precision, the one that measures 90, 100, 110 is least precise.

So what you really want is precision - reload with the same load with the same equipment and you have repeatability. You can't ignore accuracy, but as long as you are within +/-0.1 grains you are probably OK especially for most rifle loads.

An easy thing to do is to get a box of representative bullets:
- Measure a bullet repeatedly, is it always the same?
- Try several - they won't all be the same weight but most should measure the same weight every time.
- Some will be not measure the same every time. These are bullets actual weights are between what can be displayed - if your scale measures to 0.1 gr then that means the bullet's weight close to xxx.05 gr. The fluctuation indicates precision. I wouldn't expect any to measure 3 different weights.
- Repeat several times.

Evaluation:
- If you have any bullet that reads 3 different weights then the scale is highly suspect. That is, if you get readings 99.1, 99.2 & 99.3 on the same bullet then the accuracy is highly suspect. I wouldn't trust that scale.
- The fewer bullets with weight fluctuation the better your precision.

This gives a subjective evaluation. Anything more requires expensive equipment & specialized expertise.

You may want to keep the bullets that have variation. See if you get the same results under different conditions - like low charge/batteries, different ambient temperatures.
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Well Said! A batch of loads that are ALL charged 40.1gr is more important than getting 40.1gr when you intended to get 40.0gr. (ie precise vs accurate).
 
It takes no extra time to weigh to the kernal with an auto trickler. But once you get to that level you may want to take the next step and sort primers as they vary .06 . My "perfect" ammo still needs to be in a node.
 
Since I probably started todays posts I will agree that precision is the most important aspect of powder charge but it is difficult discuss because most scales do not break down the components of final accuracy. With any scale that accuracy is made up of three components, precision or repeatability, bias error trueness, and readability. Higher end scales will usually provide each of these pieces while lower end scales and automatic loaders like the Chargers will only provide the combined accuracy at 95% confidence interval.
 
It's all in the EYE of the beholder! If you don't care between .5gr & 1gr, & you are happy with your results.... congrats! If you measure down to .02gr & Happy with your results. Fantastic!! Do what works for you! Don't let anybody try to dummy-down what works for you!!
I have reloaded off & on for 40+ years. My skill has greatly increased in the last 7 years!! Why would i want to go back to what i was doing just even 10 years ago? Always try to improve!
"if you didn't learn something today, you weren't paying attention!!"
 
boomtube said:
So...what kind of scale did you use to obtain even a .03 gr resolution? Best any reloading scales I know of only claim .1 gr. accuracy! :cool:
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Creedmoor sports has a great digital scale to .01. I found my RCBS Chargemaster was inaccurate by a gr. It would show 30.3 and when verified with the Creedmoor scale it would be 29.3.
 
David Urasky said:
From a 1k F class shooter perspective, consistency is the name of the game. What the charge is is not as critical as it being the same every shot. I used an RCBS electronic scale when I started and saw my scores increase when I went to the GemPro. I got tired of having to weight the charge, then lift the pan just a little, let it settle then read the weight. Repeat that after adding or subtracting powder. I had to do that because of the friction in the scale. Then I went to the A&D 120i and now I just add powder and my scores went up again. I can take the pan with powder and move it on and off the scale a dozen times if I want and get the same value everytime. But it does only measure to .02 grains. One piece of Varget weighs about .02 grains. So to get down to .01 grains I'd have to be gutting pieces of powder in half. I use a tolerance of -0.00/+0.02 grains
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Totally agree - I did exactly what you did when using an RCBS scale (which was way better than my Hornady one). I even went one step further and after lifting the pan, I would push down on it. I spoke with some competitive shooters and they all used A&Ds, so that is what I went with. The time savings alone are totally worth the cost.

A&D scales are like AMP annealers. You can go cheap, or you can spend money and get better results in much less time.
 
10point said:
In the forum the accuracy nodes in a ladder test range between 1 to 2 grains With accuracy stable in that range. If that node is between 60 to 61 grains, and you decide to load 60.5 grains why is loading to .01 grains critical?
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Going the extra mile to .01 grains is not so much that last .01. It is more that you actually got everything in the measurement prior to that.
I use an electronic powder measure to meter my powder charges for shooting 600 yard matches. The electronic powder measure frequently drops a difference of .5 grain one way or another, usually on the minus side but occasionally on the plus side, so I take whatever the powder measure dumps into the pan and I re-weigh each charge on a scale that can measute +/- .02 grains. Yes, many of the charges are off at least .2 grains. Sometimes more, occasionally right on, but when I am trying to shoot 1/2 minute of angle at 600 yards, i want to remove as many variables as I can in my loads. I'm not a great shooter, so any small detail that might help can make a difference. I know all the poor scores are because of me, not the ammo I shoot. So there is always room for improvement. At my age, I need all the help I can get.
 
BrentM said:
Wow, I would drive myself insane trying to chase down .01 differences. I thought it was bad enough chasing .1 changes. Usually when I test loads I go in full grain increments, then split to .5 grain. I hear BR guys are nut jobs like that. LOL
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Thank you for noticing. You don't have to be OCD to shoot tight groups at mid to long range, but it helps.
 
LRNut said:
Totally agree - I did exactly what you did when using an RCBS scale (which was way better than my Hornady one). I even went one step further and after lifting the pan, I would push down on it. I spoke with some competitive shooters and they all used A&Ds, so that is what I went with. The time savings alone are totally worth the cost.

A&D scales are like AMP annealers. You can go cheap, or you can spend money and get better results in much less time.
Click to expand...
Buy once, cry once...
 

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