Scale for small charges

[rtracy2001]

I own an RCBS 5-0-2 and an Ohaus 5-0-5, both of them go up to more than 500 grains. I was taught that you should match your tools to what you are measuring so that (ideally) your expected measurement lies between 30 and 70 percent of the full range of the instrument. By this logic, the 5-0-2 and 5-0-5 should be used for charges between 150 and 350 grains. Now I imagine very few are throwing charges that heavy, and the accepted practice is to use these scales for most any charge. I really don't have a problem using them for 58 grains of 4350, but I'm not sure how I feel about 3.5 to 4 grains of Unique for my father-in-law's 32-20. To apply the 30-70 rule, I would need a 0-10 grain scale, and I have yet to see one of those.

Have any of you thought about this before?

Are any of you using a lower capacity scale BECAUSE you routinely throw smaller charges?

Is the Lee scale (100 grain capacity) my only option for a lower capacity scale?

Does the 30-70 rule not apply to the scales used for reloading? If so, why not?

[Sticky]

I have thrown low level pistol charges on an RCBS 505 for many, many years... no issues. I have electronic scales, but I find the balance more accurate and consistent for me. I can load faster with it, especially when trickling final charge weights.

Loads in the 4-5gr range have never been an issue for me with the 505.

[JSnover]

Someone working in metrology and calibration would probably agree on principle but in practice it's not an issue.

[rtracy2001]

Someone working in metrology and calibration would probably agree on principle but in practice it's not an issue.
The curse of being an engineer I suppose. [smilie=b: Thanks, all.

[mdi]

I was not the engineer, but I had to argue horse sense with some many times.:groner: Perhaps in theory your "rule" may be correct, but I have used my Lyman/Ohaus D5 for powder charges as light as 2.9 gains of Bullseye to 265 gr. cast lead bullets, checking for consistency. I have not had the opportunity to broaden that range, but expect the scale to be accurate all along the spectrum...

[C.F.Plinker]

This could apply to instruments such as meters where the scale is preprinted. When I worked for a utility all of our switchboard meters were taken to the meter lab with a blank scale. The technicians there would apply a precise current or voltage to the meter at about every 10% of the full scale value and lightly mark the blank scale. Our test crew would then ink in the graduations thereby creating a scale that was calibrated specifically for that meter movement over the full range of the meter.

You can do the same thing with your 502 and 505 by putting check weights in the pan equal to what you are trying to weigh and then adjusting the screw in the base to zero the meter. If you don't have check weights just zero it with an empty pan. In any case the range of the scale is the amount of movement of the end of the beam. The zero point is in the middle so you are working well within the 30%-70% values you mentioned it the original post.