UPDATE:
The Gemini-20 digital scale, Ohaus check weight set and the American Weigh Scales check weight sets were delivered today.
To my surprise, the American Weigh Scales check weight sets included 1 mg (.015 gr) weight when it was advertised that 10 mg (.15 gr) weight was the lowest weight. As many suggested, I ditched the batteries that came with the scale and inserted two fresh AAA Duracell batteries. After calibrating with two 10 gram calibration weights that came with the scale, I was ready to do some weighing.
To eliminate the influence of air movement, air conditioning was turned off, reloading room door closed and bench leveled. All readings were taken with the cover applied over the pan. I also only handled the check weights and pan with the supplied twizzers.
- The 10 mg (.15 gr) check weight showed .010 g consistently but when I changed the mode from gram to grains, it showed .14 gr to .16 gr (was the scale expressing its .02 gr accuracy?).
- 1/4"x1/4" pieces of 20 lb copy paper showed .06 gr consistently and 2 pieces showed .12 gr.
- The 1 mg (.015 gr) weight would not register no matter what. I finally gave up and accepted defeat that the scale was not going to detect the .015 gr check weight.
I really was hoping the scale would read the 1 mg check weight so I recalibrated the scale a few times with no success, the 1 mg check weight would not register. At least, 1/4"x1/4" pieces of paper weighed consistently.
Then I weighed the 10 mg (.15 gr) check weight on the Ohaus 10-10 scale. It consistently showed slightly higher than .1 gr. When I placed one piece of 1/4"x1/4" paper, it detected and showed between two .1 gr lines. Two pieces showed around 1 gr with the pointer never below the .1 gr line.
Summary:
Pros:
- Low price ($20)
- Lower [higher] resolution than Ohaus 10-10
- Convenient pan cover
Cons:
- Small pan (holds about 35 gr of W231/HP-38 and 30 gr of Unique)
- Small round platform (slightly less than 3/4") will not accomodate a regular pan from 10-10/5-0-5 due to ridged ring around the platform
- Gap between round platform and the scale top will allow debri to fall in
Conclusion - It's always nice to have check weights. Since the scale read the .15 gr check weight between .14 - .16 gr, I would say reading of .06 gr for 1/4"x1/4" pieces of 20 lb copy paper may be close enough to express that two pieces of paper should weigh at or more than .1 gr. So if your digital scale cannot detect two pieces of 1/4"x1/4" copy paper and you want to load max charge loads, I would likely suggest you get a beam scale that can consistently weigh .1 gr.
I will keep the Gemini-20 digital scale in my reloading room but away from the bench so it can be stored without batteries in a location that is free from shock and vibration of bench work. I will continue to keep the Ohaus 10-10 on the bench at eye level and use it to verify powder measure charges. I will also keep my FA DS-750 with flat square platform that will readily accommodate the 10-10 pan to do quick spot verification of charges and weighing of bullets/rifle cases.
Why was I concerned with .1 gr accuracy when my typical pistol charges run 3.5 - 6.0 gr? Because I load near-max/max loads with WSF. I have always trusted beam scales and check weights down to .5 gr but being able to verify accuracy down to .15 gr with check weights puts my heart more at ease.
I thank all those who participated and contributed to this thread. It allowed me to satisfy one nagging aspect of reloading that digital scales (even cheaper ones) can be accurate enough for reloading, but they need to be verified with known weights like check weights.
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