Digital Scale Comparison: GemPro 500, AY123, Sartorius GD503
This article first appeared in 2011.
JayChris, AccurateShooter.com’s IT “guru”, has tested three different digital scales. The first is the relatively inexpensive ($150.00) GemPro 500, the second was the $333.00 Sartorius AY123, which is very similar to the Denver Instrument MXX123 and Acculab-123. Lastly, JayChris tested his $1225.00 Sartorius GD503 lab scale. The 3-way comparison test produced interesting findings. We learned that the AY123 had some serious shortcomings when used to weigh powder. The GemPro 500 performed well for the price, but was quite a bit slower than the big GD503. In speed of response, accuracy of measurement, resistance to drift, and overall reliability, the GD503 was the clear winner in our comparison. Sometimes you do get what you pay for. CLICK HERE for GD503 Review with Videos.
BATTLE of the BALANCES
Three-Way Comparison Test: GemPro 500, Sartorius AY123, Sartorius GD503
Testing Report by JayChris
Precision Weighing Balances, www.balances.com, an authorized Sartorius Distributor, shipped me an AY123 (same as Denver MXX123, Acculab 123, etc.) along with a high-end GD503 force restoration scale. I had purchased the GD503, while the AY123 was a loaner for this comparison test. I included in this test a GemPro 500 scale that I already had. My key objective in this comparison test was to test each scale for measurement drift over time. We wanted to see if the displayed weight of a given object (here a certified test weight), would change over time, or with repeated measurements.
The first test was a “quick” test, where I measured the same weight ten (10) times, in the same order, about every 30 seconds or so. I did this at about the same speed as weighing out powder, maybe a bit slower. This took about 5 or 6 minutes. The second test was more-or-less an overnight test, where I measured the same weight in lengthening intervals, starting every 10 minutes, then every 30, then every 60, and so on. You can see the time series on the included graphs.
TEST SETUP:
– I used the same 100 GRAM Sartorius certified check weight for every test (see photo). Note: 100 GRAMS = 1543.233 GRAINS
– I calibrated each scale within 30 seconds of each other before starting the test.
– I tare’d each scale within a few seconds of each other
– All three scales are connected to the same line conditioning PDU and are located in the same environment (right next to each other)
Measurement Resolution and Display Increments
– The Sartorius AY123 measures to the nearest hundredth of a grain (.00). Increments are in 0.02 grain divisions, i.e. the nearest two hundredth of a grain.
– The Sartorius GD503 measures to the nearest thousandth of a grain (.000). Increments are in 0.005 grain divisions, i.e. the nearest five thousandth of a grain.
– The GemPro 500 measures to the nearest half-tenth of a grain (.05).
NOTE: When weighing powder, I weigh to the nearest .05 grain so any of these provide adequate (or more-than) resolution.
FIRST SERIES Quick Test:
* X-axis is weighing series iteration
SECOND SERIES Time-based:
* X-axis is a time series in minutes-from-0.
THIRD SERIES AY123 “Stable” vs. “Unstable”:
* X-axis is a weighing series iteration
This is a test of the AY123 in “Stable” vs. “Unstable” environment mode. The GD503 was used for comparison. I ran this test to compare the AY123 in “Stable” conditions mode (default) vs. “Unstable” conditions mode, based on anecdotal reports that the “Unstable” mode produces more consistent results. I did not find that to be so. In addition, I found that the weighing time for the “Unstable” mode was extremely slow — taking nearly 5 – 7 seconds per instance to complete a measurement. It then takes a few seconds to return to zero. In the AY123’s default “Stable” mode, it takes a second or so. Based on my testing then, there is no advantage to running the AY123 (or similar clones) in the “unstable mood”. It will simply slow you down.
Observations and Conclusions
Overall, the GD503 was the most consistent, never varying more than .005 (five-thousandths) of a grain, which is about ten times less drift than the next closest scale. The GemPro was “close” behind, never varying more than .05 of a grain. The AY123 was consistently variable and lost significant resolution over time. It was difficult to plot the AY123 results because it rarely settled at a weight for longer than a few seconds — it would routinely come up with a different weight every few seconds, varying by as much as .04 of a grain. I selected the first reading it “settled” on as the “official” reading.
The one thing this test does NOT demonstrate is trickling — our previous Review of the GD503 has a video that shows that nicely. The GD503 gives you near instantaneous read-outs when trickling. By contrast, both the AY123 and GemPro 500 require a “trickle-and-wait-for-update” plan. The GD503 is really dramatically better in its ability to return a “final” weight very quickly. This allows efficient trickling. CLICK HERE for GD503 Review with Videos.
[UPDATE: One of our readers observed that there is a setting which can make the AY123 more responsive (and accurate) when trickling charges: “Note that the video shows the 123 jumping as powder is added. The reason is the scale is in the default setting, which is for single weightings. When changed to ‘Filling’ mode, the scale reacts very quickly, and in my case accurately. Trickling is easy in the ‘Filling’ mode. My experience is that the AY123 is an excellent scale, but is sensitive to environmental factors. The GD503 is way better and is also way more expensive.” — Matt P.]
GemPro 500 Performed Well — Drift Was Usually Minimal and Charges Settle Fairly Quickly
I’ve used the GemPro 500 for quite a while now and have found it to be fairly reliable. However, over one previous loading session I have seen it drift as much as .150 of a grain. I had to go back and re-weigh charges because of this. Therefore, I tend to tare it every five (5) weighings or so which is probably overkill based on one case. I’ve not had that problem since so I am guessing something happened environmentally (maybe I bumped it or something). Overall, the GemPro is not overly sensitive to environment and settles fairly quickly and reliably.
Charges Weighed by SD503 Have More Consistent Velocities, with lower SDs
I’ve loaded a few hundred rounds with the GD503 now. I have not found it to drift more than .010 of a grain in that time. So, now, I only tend to tare it once at the beginning of a load session. I have gotten extremely consistent velocities from charges loaded with this scale, with single-digit standard deviations. By contrast, previously, my best efforts usually resulted in standard deviations (SDs) in the low teens.
Based on my experience testing the AY123, I would not choose this scale to load powder with. The readings are just too variable. The slightest environment factors (breathing, hand movement, etc.) cause large changes in results. I tried to load some rounds using this scale (backed by my GD503 to verify) and I couldn’t do better than a few tenths of a grain, and that was with considerable effort. The Sartorius AY123 is really the wrong tool for the job when it comes to measuring powder.
Thanks to Precision Weighing Balances for providing the AY123 for comparison. The other two scales, the GemPro 500 and GD503, I purchased on my own nickel. [Editor’s Note: When purchased in 2011, Jay’s GD503 cost approximately $900.00. The current 2012 price at Balances.com is $1225.00.] All three of these digital scales can be purchased through the Precision Weighing Balances webstore:
GemPro 250 | GemPro 500 |AY-123 |GD503
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Tags: Acculab, AY-123, AY123, Balance, GD503, Gem Pro, GemPro 250, GemPro 500, MXX-123, Sartorius, Scale, Test
I have a AY123, and could not duplicate the above results. My scale is extremely accurate. Environmental conditions are important with this scale. The room I use has a constant temperature and humidity. My steel bench is bolted to the wall, and rests on a concrete floor. I leave my scale plugged in but not on.
In over 30 measurements of 141gr, 28 were exactly 141, and 2 were 141.02. After three days, I had no drift, and performed the test again, with the same results.
Note that the video shows the 123 jumping as powder is added. The reason is the scale is in the default setting, which is for single weightings. When changed to ‘Filling’ mode, the scale reacts very quickly, and in my case accurately. Trickling is easy in the ‘Filling’ mode.
My experience is the AY123 is an excellent scale, but is sensitive to environmental factors. The GD503 is way better and is also way more expensive.
Have often wondered why calibration to a weight of 100 grams makes any sense when charge weights are usually less than 100 grains (even for African game calibers.
I would think that calibration weights should either fall within the range of charge weights (presumably at the middle) or at the top end of the range.
This is great info on digital scales.
What about the average Joe, you know the guys that bought a RCBS digital scale and powder dispenser combo, or the other brand equivalent?
How accurate are they in comparison to the lab equipment?
100 g = 1543.233 gr
gram to grain conversion
A calibration weight has no relationship at all to weighing operations (i.e., it makes no difference what size the calibration weight is, as long as your scale can support the weight). All a calibration weight does is allow your scale to be “calibrated” against a known, “guaranteed” weight. Could be 20g, 50g, 100g… doesn’t matter as long as that calibration weight is certified to be that specific weight. Using a 100g certified weight or a 1g certified weight is not going to make any difference in the subsequent weighing outcomes, whether light powder loads or otherwise, assuming the calibration weights are certified.
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Have often wondered why calibration to a weight of 100 grams makes any sense when charge weights are usually less than 100 grains (even for African game calibers.
I would think that calibration weights should either fall within the range of charge weights (presumably at the middle) or at the top end of the range.
When weighing powder, I do not see the practical value of a 0.005 gr accuracy. We’re measuring powder, not plutonium.
As long as it is around 0.1 gr, of the baseline charge, I’m happy. I don’t care if that, say 30.8 gr is really 30.9 as long as it is repeatable from day to day.
I guess some folks are measuring something other than powder.
There is another technology used for weighing precisely that I have never seen referenced on this web site called tuning-fork sensor Analytical Balance. The one I have is made by a company called Vibra and it is amazing.
Here’s a web site for you. http://www.vibra.co.jp/global/products/analytical/ht_htr/index.html
I have one of these and have found it to be incredibly stable and is impervious to magnetic interference from items like nearby cell phones or space heaters. The model I have was a bit pricey but has internal automatic calibration that initiates on startup.
I bought mine from a dealer in Montreal.
A tuning fork balance has many advantages over load cell or magnetic force reconstruction balances so have a look.
“Could be 20g, 50g, 100g… doesn’t matter as long as that calibration weight is certified to be that specific weight.”
This is simply wrong. All a calibration weight does is verify that the scale is accurate at that weight. It can not guarantee that a weight far from the calibrated weight is accurate. Even with two calibration weights, there is no guarantee of accuracy between those two points, but you do have significantly fewer possible sources of error than with just one point. Before a loading session, and after calibration, I always verify the accuracy using weights within about 25% of my desired charge weight.