crbutler wrote:Sam, you have been saying that for some time, and you are wrong.
Your measurement is still only good to 0.1. You need a better scale to go to a second significant digit... I can pull the analytic chem book out to quote chapter and verse if you wish. You have it right that a cheap electronic is somewhat inaccurate, but on the other hand, a cheap electronic is easy to use and will encourage folks to check more frequently. I guess I am trying to say that the cheap scales have a place in a beginner's kit, as long as you follow directions and work up, you won't get in trouble with it.
As to the power measure question... For general purpose reloading (no African guns or .50 BMG) I have had good luck with a plain old RCBS. I did get a Harrel for playing around with accuracy loads, but mostly for accuracy and big game hunting use a Chargemaster. Both of those are spendy as is something like Erud's Prometheus. For someone just starting to do more variety, I would go with the RCBS, although some folks really like Hornady's.
crbutler wrote:You miss the point.
Mathematically you are right. (X+X+X+X+X+X+X+X+X+X)/10 = X
Statistically you are not correct. 10 (~X)/10 is not X... it is ~X. You are trying to indirectly measure ~.
As pertains to measurement you are wrong. You HAVE to preserve significant figures. If I measure 10 objects with a yard stick, I can't figure out how big they are to the inch, I have to say it is to the closest yard, no matter how many of them I measure.
Vey poor analogy. A yard stick is 36 times bigger than an inch, not 10 times bigger, and every yard stick I have ever seen has inch markings on it. Are you talking about a 36 inch long 2x4??
You can't say the scale is off by 0.02 grains by your averages method, you are inducing a rounding error calculation in your measurement, not a true measurement of the error.
Ummmm, excuse me, but I'm talking about the weight coming from THE POWDER MEASURE, and NOT the scale!!!
I in no way have ever inferred that you can get an extra decimal point in accuracy from your scale, but by averaging 10 charges you CAN get that extra decimal point on the accuracy of THE AVERAGE weight of the power thrown FROM THE POWDER MEASURE!!! This method is for setting a powder scale to deliver, ON AVERAGE, 12.4 grains of powder dead nuts on, and not .02 or .03 grains off on the AVERAGE, which you approximate by weighing 10 charges together. This method is a hell of a lot better than throwing one charge from a measure, weighing that single charge at 12.4 grains, and calling it good. You know as well as I do that powder measures are very inexact devices, and things such as settle time, vibration, throw speed, and return throw speed can significantly effect the weight thrown.
Your method SOUNDS good, but it is scientifically invalid.
Once again, you seem to have missed my basic premise that this concerns the average weight coming out of the powder measure, and I have NEVER said that you can by some trick get an extra decimal point of measurement OUT OF YOUR SCALE.
Admittedly if you measure enough items, you can gain some significant figures...for what you are doing, you need at least 100 (to get the 3 significant figures, which probably puts you over the max capacity of your scale...)
This is basic statistics.
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