RCBS model 90 electronic scale

[dieselten]

I have an old RCBS electronic scale made by Ohaus. It is a model 90 with a reading to only the first decimal place. It has served me well for over 15 years. I have lost the calibration weights, but I am not sure the scale needs to be calibrated. I just weighed several bullets each:

Sierra 6.5mm 142 BTHP at 141.8
Sierra .30 caliber 190 BTHP at 189.9
Sierra 6mm 107 BTHP at 106.9-107.0
Berger 6mm 80 flat base at 79.9 (scale floats between 79.9-80.0 for each bullet then settles on 79.9)

I have never calibrated this scale in all the time I have had it. I always just weigh whatever bullet I am using and see what it says. It has always been as close now as it was the day I got it.

My question, based on my above readings, is my scale accurate considering only 1 decimal place readout? What are you guys with NASA scales getting for the weight of these bullets?

I also have a small jewelers electronic scale with 2 decimal place readout and after comparing the 2 scales they consistently read .06 apart with the RCBS on the low side.

The check weights I am missing are two 250 grain weights. If I got my hands on some Sierra or some other 250 grain match bullet, would that be suitable for scale calibration? Anyone have 2-250 grain match bullets they can spare?

Thanks

 

[dieselten]

any one?

 

[Preacher]

Let me see if I can help you with that.
I'll look and see what I can do for 2 250 grain weights.
PM me a good mailing address to send them to...
The model 90 should be calibrated every time it's moved...
These will be checked with a GD-503...

 

[jlow]

I don’ use any of those bullets you quoted but using my GemPro 250 the last time I prep my rounds with 175 SMK and weighting 14 bullets, this is what I found:

Average weight = 175.22gr
Extreme spread = 0.12gr
SD= 0.04gr

Having weight thousands of SMKs, I can tell you that they are in general very consistent but that does not mean that they don’t have the occasional defective ones in there with real high, low weights, and distored ogives thus the rationale to sort.