Gempro 250

[live 2shoot]

123stores.com has the gempro 250 on sale for $100 plus tax and free shipping.

 

[Mozella]

The Gempro 250 is a low cost way to measure powder to to better than a tenth of a grain. It has quirks which you have to work around. For example, it doesn't react to trickling nearly as well as you might hope, so you must develop a technique to overcome that flaw.

Having said that, I use my Gempro 250 for each and every competition load and every test load where I'm trying to eliminate any possible variation in powder charge because my RCBS Chargemaster is simply not accurate enough.

If you need (or think you need) a scale with .02 grains resolution, then I'd say go for it. A hundred bucks is a good price.

 

[Hengehold]

The Gempro 250 is a low cost way to measure powder to to better than a tenth of a grain. It has quirks which you have to work around. For example, it doesn't react to trickling nearly as well as you might hope, so you must develop a technique to overcome that flaw.

Having said that, I use my Gempro 250 for each and every competition load and every test load where I'm trying to eliminate any possible variation in powder charge because my RCBS Chargemaster is simply not accurate enough.

If you need (or think you need) a scale with .02 grains resolution, then I'd say go for it. A hundred bucks is a good price.

I was going to get one of these. What do you have to do to accommodate for the slow reading after trickling?
Thanks.

 

[MNFinn]

I was going to get one of these. What do you have to do to accommodate for the slow reading after trickling?
Thanks.

I just pick up the tray and set it back down after a trickle. It slows me down a bit, but not much, and is faster than waiting for the scale to pick up the difference.

 

[jlow]

I was going to get one of these. What do you have to do to accommodate for the slow reading after trickling?
Thanks.

The proper way to do this is to fine tune powder on the scale with a small powder spatula (ball powder) or a pair of tweezers (extrudes). After you add the powder, place the tip of the spatula/tweezers gently on the weighting pan so that it over scale slightly. Immediately take it off and the weight will stabilize and give you the proper reading. Done this way, the scale is as fast and accurate as any scale out there.

 

[Mozella]

The proper way to do this is to fine tune powder on the scale with a small powder spatula (ball powder) or a pair of tweezers (extrudes). After you add the powder, place the tip of the spatula/tweezers gently on the weighting pan so that it over scale slightly. Immediately take it off and the weight will stabilize and give you the proper reading. Done this way, the scale is as fast and accurate as any scale out there.

That's how I do it; however, this trick only works once or twice as you add or subtract a kernel or two to hit the exact target weight, or exact to .02gr anyway. If you fiddle with it too many times or for too long a time, you will find that the scale gets lost, so to speak. If you put the charge into the case and then set the empty pan on the scale, it may not go to zero or, if it does, it takes a while to do so. Then if you re-tare the scale and re-weigh the previous charge, you may find it off by a few hundredths of a grain or sometimes more. I'm not sure this is technically "drift", but it is definitely a potential problem. Perhaps a scale guru will chime in.

A RCBS Chargemaster comes in handy here because it often produces a load within a few kernels of your target. Consequently, correcting the charge is quick and easy because usually only a few kernels are required rather than genuine trickling.

So, assuming I'm going for the best precision, if I can't hit my target on the first or second fine correction, I charge the case, zero the scale, dump the charge onto the scale again, and reweigh to be sure.

Another technique to speed up things when you're making "good plinking" ammo, as opposed to competition ammo is to take the result from the RCBS Chargemaster, check it on the Gem Pro, and make a correction based on your experience. For example, with medium extruded powder where the sticks weigh about .02gr each and if you are .04 gr under or over target, just toss in or remove two kernels and charge the case without waiting for the Gem Pro to settle down. Use three kernels for a .06gr error and so on. Of course, outside that range, your "good plinking" ammo might turn into "fouling rounds"; you get the idea.

Bottom line: The Gem Pro is a good value, but you have to treat it like a high maintenance girlfriend with a nasty drug problem and a troubled childhood.

 

[jlow]

That's how I do it; however, this trick only works once or twice as you add or subtract a kernel or two to hit the exact target weight, or exact to .02gr anyway. If you fiddle with it too many times or for too long a time, you will find that the scale gets lost, so to speak. If you put the charge into the case and then set the empty pan on the scale, it may not go to zero or, if it does, it takes a while to do so. Then if you re-tare the scale and re-weigh the previous charge, you may find it off by a few hundredths of a grain or sometimes more. I'm not sure this is technically "drift", but it is definitely a potential problem. Perhaps a scale guru will chime in.

A RCBS Chargemaster comes in handy here because it often produces a load within a few kernels of your target. Consequently, correcting the charge is quick and easy because usually only a few kernels are required rather than genuine trickling.

So, assuming I'm going for the best precision, if I can't hit my target on the first or second fine correction, I charge the case, zero the scale, dump the charge onto the scale again, and reweigh to be sure.

Another technique to speed up things when you're making "good plinking" ammo, as opposed to competition ammo is to take the result from the RCBS Chargemaster, check it on the Gem Pro, and make a correction based on your experience. For example, with medium extruded powder where the sticks weigh about .02gr each and if you are .04 gr under or over target, just toss in or remove two kernels and charge the case without waiting for the Gem Pro to settle down. Use three kernels for a .06gr error and so on. Of course, outside that range, your "good plinking" ammo might turn into "fouling rounds"; you get the idea.

Bottom line: The Gem Pro is a good value, but you have to treat it like a high maintenance girlfriend with a nasty drug problem and a troubled childhood.

Mozella – I’ve never seen the scale “get lost” and I’ve used mine longer than probably anyone on this board (more than 5 years). The scale does not keep track of how many times you do this, all it knows is you have added weight and it goes and equilibrate and gives you the number.

My scale zeros in a second and only needs a re-tare maybe once in 5-6 weighting and this is only because it is off by 0.02 grains.

 

[raptor1ronin]

Love my Gempro 250!

 

[Hengehold]

Well, I hope you guys are right. I just bought one.

 

[Mozella]

Mozella – I’ve never seen the scale “get lost” and I’ve used mine longer than probably anyone on this board (more than 5 years). The scale does not keep track of how many times you do this, all it knows is you have added weight and it goes and equilibrate and gives you the number.

My scale zeros in a second and only needs a re-tare maybe once in 5-6 weighting and this is only because it is off by 0.02 grains.

I didn't mean to imply that it keeps track of how many times you add or subtract weight. But, mine at least, will go out of calibration in a relatively short period of time when you add or subtract weight. Usually the time window for a "good" result is about the time it takes to make two corrections. I should have made that more clear; the "drift" seems to be a function of how long you fiddle around and/or trickle.

Try this experiment: You would hope that you could dump 25 grains of powder and then slowly trickle up to 26.00 grains over a period of one minute and still have an accurate result, even if it might require you touch the pan lightly from time to time. But when mine gets to 26.00 grains, it usually turns out to have slightly more or less than that in the pan. When I empty the pan and place it back on the scale, the scale sometimes doesn't return to zero and other times it shows something significantly different than zero but over a period of 10 seconds or so it will eventually find zero. Resetting the tare and re-weighing the previous charge, which moments ago indicated 26.00, might now show 26.05 or some other error. A small error happens nearly every time I find myself adding or subtracting weight if it takes more than a short period of time. I don't know if that's technically "drift", but mine certainly requires a learned technique to produce precise charges.

In other words, fiddling around correcting a charge will produce errors if not completed quickly.

On the other hand, the repeatability is very good. A charge of 25.00gr can be removed and put back into the pan a number of times and it shows the correct weight each time, assuming you give it a moment to find zero when you put the empty pan on the scale.

 

[jlow]

That’s interesting since my usually return to zero after I weigh a charge. Do you do all the calibration – both linear and single point?

 

[Mozella]

That’s interesting since my usually return to zero after I weigh a charge. Do you do all the calibration – both linear and single point?

Mine usually returns to zero too but not always. As far as calibration, point calibration, yes. Linear, no because the manufacturer recommends doing a linear calibration only if the load cell is changed.

But the problem isn't associated with calibration anyway. It has to do with the inability to properly measure dynamic changes in weight; the kind you get with trickling or charge correction.

Here's a review on the scale which points out the same defect I mentioned in my previous posts.
https://preciseshooter.com/blog/ScaleReduxPart3GemPro250.aspx

 

[1newmexkid]

When I used a GemPro and I was within what I figured was 1-2 kernels of desired weight I would use some tweezers to add them. I would add the final powder with what I can best describe as a throwing motion of the powder into the pan. The Gempro would respond almost instantly.

 

[wzee]

When I used a GemPro and I was within what I figured was 1-2 kernels of desired weight I would use some tweezers to add them. I would add the final powder with what I can best describe as a throwing motion of the powder into the pan. The Gempro would respond almost instantly.

dont waste your money on a gempro ,I had one had to send it back they send me a new one . went thru this 3 times ,the gempro drifts more than the snowstorms in pa. buy a&d fx-120i and cry ones

 

[live 2shoot]

"Bottom line: The Gem Pro is a good value, but you have to treat it like a high maintenance girlfriend with a nasty drug problem and a troubled childhood."

Thats awesome Mozella!

There is not doubt that this scale uses very sensitive transducers. The environment of the work area will most likely determine the accuracy of the scale. You prob need a room with good temp control, no drafts, solid flooring and table. Just closing the lid created a .12 gr addition. The scale would re-zero after i lifted the lid. So far It looks like a solid product.

 

[jlow]

Mine usually returns to zero too but not always. As far as calibration, point calibration, yes. Linear, no because the manufacturer recommends doing a linear calibration only if the load cell is changed.

But the problem isn't associated with calibration anyway. It has to do with the inability to properly measure dynamic changes in weight; the kind you get with trickling or charge correction.

Here's a review on the scale which points out the same defect I mentioned in my previous posts.
https://preciseshooter.com/blog/ScaleReduxPart3GemPro250.aspx

Thanks for the additional info. Been busy out shooting today! Like I said, up to now, I have not had a problem with the scale but will take a further look based on the new info when I have a some free time.