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September 9th, 2012

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.

digital scales GD503, AY124, GemPro 500 250

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.

digital scales GD503, AY124, GemPro 500 250

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:

digital scales GD503, AY124, GemPro 500 250

* X-axis is weighing series iteration

SECOND SERIES Time-based:

digital scales GD503, AY124, GemPro 500 250

* X-axis is a time series in minutes-from-0.

THIRD SERIES AY123 “Stable” vs. “Unstable”:

digital scales GD503, AY124, GemPro 500 250

* 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

Permalink Gear Review, New Product, Reloading 8 Comments »
August 5th, 2011

Review of the GemPro 250 Scale (from My Weigh)

Gempro 250SUMMARY: This review gives high marks to GemPro 250 scale from My Weigh. It offers 0.02 grain resolution, good enough to trickle kernel by kernel. At just $165.49, the scale is quite affordable. The GemPro 250 comes with a lifetime warranty for American buyers. As this scale weighs more precisely than popular digital powder scale/dispensers, you can use the digital dispenser to throw a “close” charge and then fine-tune your load with the GemPro, kernel by kernel.

by Bill Schnauffer (aka Cover Dog)
The Importance of Precise Loads for Long-Range Shooting
The reloading scale is the life blood of anyone’s loading bench. It’s used for everything from weighing powders to cases or bullets and yes even primers. I would have never considered weighing primers but that is one of the many things I learned the weekend of May 20-22, 2011 at The Original Pennsylvania 1000-Yard Bench Rest Club’s Bench Rest Instructional School. All aspects of reloading for 1000-yard BR have to be identical. Your brass, bullets, powder and primers all have to weigh the same, for all your sighters and your 10 record shots, if you want any chance of being competitive. This can only become a reality if your scale is up to the task. Everything you do when shooting at 1000 yards is magnified 10x and your scale needs to be above all else, accurate and repeatable.

Gempro 250

I thought that a scale accurate to 1/10th of a grain was good enough. Not so in the long range BR game. Scales need to be accurate to at least 5/100ths of a grain or better if you can afford it. This prompted my search for such a scale.

GemPro Is Half the Price of Denver Instrument MXX-123
I have read reviews for several of the better scales used for reloading including the Accu-Lab VIC 123 (Accu-Lab ceased operation Dec. 31, 2010) and its predecessor the Sartorius AY-123. The scales are identical just repackaged and with a new name and color. The scale is accurate to 2/100ths of a grain, but is also a scale that many felt was affected by RF interference and the slightest air movement made it drift. This was due in part because of the strain gauge technology that is used in the manufacture of this scale. And with parts not readily available, the lead time for one is you want it is over 20 weeks. The Denver Instrument MXX-123 also had a good review but like the others above, it’s into the $320 price range. And this is out of reach for many reloaders.

This now brings me to the My Weigh GemPro 250. It uses True-Division German HBM sensors and professional components in the manufacture of this scale. It has a 50 gram weight capacity (771.72 grains) and accuracy down to 2/100ths of a grain. It features seven (7) weighing modes as listed below. And with a retail price in the $165.00 range, this is a scale that most reloaders could afford for their reloading bench. And you won’t be pressed for room on that bench. The scale is very compact, measuring 5.25″ X 3.75″ X 2.5″.

Gempro 250

NOTE: There is also a GemPro 500 which has a weight capacity of 100g (1543 grains) but only has accuracy down to 5/100ths of a grain.

Testing and Evaluation
I decided to give the GemPro 250 a try. Several days after I placed my order, Big Brown arrived. As I started to unpack the scale my heart started to sink and the first words out of my mouth were “boy is this thing small, hope it wasn’t a mistake”, only time will tell.

Gempro 250

Included with the scale was a plastic travel case that housed the accessories. They consisted of an AC power supply, ASTM class F2 calibration weight, weighing pan, plastic tweezers and a vibra-kill pad. The scale also has a built in circular bubble level, four leveling feet, hinged protective windscreen and a stainless steel weighing platform. If you load at the range, you’ll be glad to know that it also runs on four AAA batteries. Information sheets that came with the scale stated it takes the load cell one hour to come up one degree in temperature when plugged in and turned on. Instructions recommend giving the unit a 24-hour warm-up before use.

Gempro 250Scale Calibrates Rapidly
After leaving the scale on for 24 hours (my scales are always up and running), I placed the ASTM class F2 20g calibration weight on the scale after setting it to calibrate. After about 3 seconds it stopped its calibration and read 20.000g exactly what the calibration weight was supposed to weigh. When converting grams to grains you need to multiply by 15.4324 or with this scale you can just scroll through the seven weighing modes until you come to grains. Its actual weight is 308.65 grains but since this scale only reads to 2/100ths of a grain the 100ths digit must always be an even number, so it reads 308.64 grains.

For the next several minutes I started weighing everything I had in front of me. Bullets, brass, loaded rounds all were gathered up and weighed so I could get the feel for the GemPro 250.

I set the calibration weight on the scale between every one of the 30 loads I weighed. Only once did it vary from the 308.64 grain reading when it moved up to 308.66 grains.

I wish I had at my disposal a scale more sensitive than the GemPro 250 to double check its accuracy. Scales that read to 1/100th of a grain are out of my price range, and cost from $2000 for the Citizen CX265 to $4065 for the A&D Phoenix GH252. I purchased a PACT Digital Scale in late 1994 and to this day it has been my “go to” scale. In 2002 I sent it back to PACT to have the infrared port installed so I could purchase PACT’s infrared powder dispenser. I have used the PACT Scale/Dispenser as a team for the last 10+ years for all my reloading needs. So now with the GemPro 250 on my bench it was time to see how “accurate” my reloading with the PACT combo has been.

Gempro 250 scale

Editor’s Note: In this review, the GemPro 250 is used to confirm the weight of powder throws from a PACT digital dispenser. However, the reviewer did not have a laboratory-grade scale to test the displayed weights from the GemPro 250. We have another GemPro 250 on order from Amazon.com. When it arrives we will do a comparison weighing test, using a Denver Instruments lab scale as the control unit.


Gempro 250 scaleREAL WORLD TESTING
Double-Checking PACT Dispenser with GemPro 250
For the first test I used Reloder 15 (RL15), a course, long-kernel powder. After calibrating both the PACT scale and the GemPro 250 I set the Pact Dispenser to throw a charge of 27.7 grains. During the throws, if the PACT scale read 1/10th over/under, I didn’t make any correction. I just waited until it stopped dispensing and the transferred the charge in the pan to the pan in the GemPro 250.

Below are the results of those 10 thrown charges:
27.76 | 27.94 | 27.80 | 27.84 | 27.92 | 27.88 | 27.76 | 27.88 | 27.78 | 27.78

Note: As measured by the GemPro 250, none of the PACT throws hit the 27.7 grain mark exactly — all throws were slightly high. The total spread from lowest (27.76) to highest (27.94) throw was 0.18 grains and the spread from the 27.7 target weight to the highest dispensed charge was 2.4 tenths of a grain HIGH. I’m sure this could cause a little vertical at 1000 yards.

For the next round of tests, I used IMR 8208 XBR. Compared to RL15, the kernels of 8208 are shorter in length and smaller in girth. Using the same parameters as with the RL15, here are the results of 10 thrown charges with IMR 8208 XBR:
.
27.78 | 27.80 | 27.78 | 27.82 | 27.78 | 27.84 | 27.80 | 27.74 | 27.78 | 27.74

Once again, not one of the 10 dispensed charges were right on the mark according to the GemPro. Again, all thrown charges were slightly hight.The range from target weight to the highest was 1.4 tenths of a grain, and the total variance from 27.70 grain target weight was 0.14 grains.

The final powder tested was HS6. This is a spherical powder which, by most accounts, meters very well. With the same procedures in place here are the results for HS6 weighed on the GemPro 250:

27.76 | 27.74 | 27.74 | 27.78 | 27.68 | 27.74 | 27.70 | 27.74 | 27.68 | 27.70

As expected HS6 did very well in getting close to the 27.70 target and hit it on several throws. The total variance from the 27.70 target Averaging 26/100ths over for the 10 charges thrown

PACT Performance Re-Evaluated
Only able to read to 1/10th of a grain, the PACT dispenser looked to be nearly perfect with the HS6 powder. But when checked with a precision scale capable of reading to 2/100th’s of a grain, I found that the PACT still threw loads that were higher than what was programmed. I will still use my PACT to dispense my loads one grain short and then trickle in the last few kernels with the scale pan sitting on the GemPro 250.

CONCLUSION
The GemPro 250 is small, compact, portable and able to deliver repeatable accuracy to 2/100ths of a grain, time after time. That is all that one can ask of any scale. There is one last important thing to mention. The GemPro 250’s express warranty is LIFETIME (for domestic buyers) or 30 years for International Customers. A lifetime warranty is unheard of in the electronics business. I guess the people at My Weigh know what they have and are willing to stand behind it. If it should ever need servicing the My Weigh service center located in Phoenix, AZ will repair your scale and have it back to you in two business days.

Permalink Gear Review, Reloading 4 Comments »