Check Weight for Scales

[Ganderite]

Before a loading session I like to make sure the scale is correct. And in a long loading session, I like to check again.

Using my GEM250, measured to the 1/100th of a grain, I sorted through some 55 gr bullets to find 2 that were exactly 55.00 gr. (One needed a light pass on the tip to get it down to 55.00)

Each bullet now sits on a little folded pad of masking tape on each scale.

I know I could have used the zero weight that came with the scales, but I am measuring powder charges around 45 gr, so would rather check weight with a 55 gr weight than a 250 gr weight.

 

[CranePete]

That’s a great trick! Thanks for sharing.

 

[Andy]

It's more important that the scale is consistent than accurate, i.e. it's better to throw 49.8 grs +/- 0.05 grs than 50.0 grs +/- 0.1 grs.

The fact that you record your most accurate load as 50.0 grs, when it's actually 49.8 grs is meaningless.

 

[South Pender]

Before a loading session I like to make sure the scale is correct. And in a long loading session, I like to check again.

Using my GEM250, measured to the 1/100th of a grain, I sorted through some 55 gr bullets to find 2 that were exactly 55.00 gr. (One needed a light pass on the tip to get it down to 55.00)

Each bullet now sits on a little folded pad of masking tape on each scale.

I know I could have used the zero weight that came with the scales, but I am measuring powder charges around 45 gr, so would rather check weight with a 55 gr weight than a 250 gr weight.

That's probably a good way to keep your weighing fairly consistent. However, what you have established is that your scale indicates that the two bullets weigh 55 grains, not that they actually weigh exactly that. Your scale could be a out a bit—say +.2 gr.--and show 55.0 gr. for the two bullets when, in fact, they actually weigh 54.8 gr. Not a big deal to be sure, but be clear on what you have established with this procedure. If you want your scale to indicate exactly what something weighs, you need really precise calibration weights. I've discussed this in another thread. I got an F2-class calibration weight from Transcat.for around $45. This has a tolerance of .009 grains. I’ve used it to calibrate my scale, and I use it before each loading session.

Just a couple of additional small points. If by GEM250 scale you meant the Gem Pro 250 (rather than the RCBS scale in your picture), I believe that it is accurate to within .001 grams. This means you it gives you .02 grain resolution. As for checking for accuracy, the recommendation I've seen is to use a weight for this purpose that is much heavier than the weights you will be working with. My F2 calibration weight is 10 grams or 154.32 grains, and the range of powder charges I'm weighing tend to be in the 25-gr. to 70-gr. range.

 

[Ganderite]

" If you want your scale to indicate exactly what something weighs, you need really precise calibration weights."

Yup. That is why I used a calibrated scale to the 1/100th of a grain to measure the bullets.

Using my GEM250, measured to the 1/100th of a grain, I sorted through some 55 gr bullets to find 2 that were exactly 55.00 gr.