I tested accuracy of my scale

[madman25]

this should be some neat information regarding accuracy and repeatability of reloading scales.

the scale i have been using is a lyman 500

i have another scale i recently was given, a mettler H15, this is 40 years old, but i have callibrated it, it has a 160 gram +/- 0.0001 grams, a very accurate scientific scale, atleast compared to reloading scales

I decided to conduct a little test, dump and trickle 10 charges, 43.2 grains set on lyman scale, or 2.7993 grams, i then measured the charges in the H15 scale.

I got, in grams

2.7948 2.795 2.7968 2.8005 2.8008
2.7994 2.8005 2.7993 2.7971 2.801

min is 43.13 grains max is 43.22, a span of .09 grains, basically a tenth of a grain error

now the kicker, i counted and weighed 20 granuals of the poweder (varget) and found they weighed 0.00143 grams each

so the min charge was approx 1954 granuals, the max was 1958, a span of only 4 granuals

i found this amazing, so best posible acuracy would be +/- 0.025 grains

now i reload 50 shells to all have +/- 1 granual using H15 scale, see if they are more accurate, doubt it, but i will try

 

[Boomer]

I think you will find that your loads won't be much more accurate. Your cases and bullets would also have to be almost identical, and there are other elements to accuracy than exacting powder weight. Bullet and case concentricity and uniformity, neck tension, primer pocket and flash hole uniformity, and how you hold your tongue when you shoot immediately come to mind.

This is not to say that I discount your efforts towards uniformity. Anything we can do to limit the variables helps the over all picture, and I would rather have a scale which would measure to within .10 grains rather than one which measures +/- .10 gr. Seems like you have that beat all to hell.

 

[tiriaq]

This kind of uniformity may be worthwhile at long range, where any variation in velocity can result in vertical spread.

 

[madman25]

yea there are allot of other variables, i previously sorted all my brass by weight, when they all were the same length ans had been fired in my chamber, no more than .5 grain spred in cases, that made a huge difference, i was really happy with that, and you only need to do it once, flash holes are all done, bullets are 178 amax, so neck tension is the only other one i have to do.

totally the case here with the lyman that it is pretty much imposible to make out the spred i saw in weights, .1 grain spread when the scale is marked to be able to decifer that, is sorta lame

 

[Max Power]

I think you will find that your loads won't be much more accurate. Your cases and bullets would also have to be almost identical, and there are other elements to accuracy than exacting powder weight. Bullet and case concentricity and uniformity, neck tension, primer pocket and flash hole uniformity, and how you hold your tongue when you shoot immediately come to mind.....

Thats whats killing my accuracy- I'm not placing my tongue consistently!

Cheers Boomer for making me laugh on that one... You also made me recall and old G&A with a guy trying to build a 1 MOA revolver. He had methods to quantify and ensure consistancy for all the things you mentioned and more. He even went so far as to orient all the headstamps the same way in the cylinder when firing. Seemed like overkill when I read it but I now understand even the smallest of details can have an effect on accuracy at that level.