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Speed up your powder weighing with a GemPro250

Sheldon N

Blind Squirrel Finds a Nut
Full Member
Minuteman
Sep 24, 2014
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3,901
Pacific Northwest
So lately I'm weighing charges with a GemPro250. I've found the scale very accurate and very consistent (within 0.02 grain, one kernel of Varget) and weighing powder charges to the kernel has helped my ES and SD on all my rifles. The only downside is that weighing to the kernel can be a tedious and slow chore. Having gone through a couple different scales I've been able to try out a few different techniques and I think I've found one that is both accurate and fast. I thought I would share it in case it might be of any assistance to anyone else.

I can currently meter out powder charges for a block of 50 cases, accurate to +/- 1 kernel of powder in ~18 minutes. Bullet seating goes pretty quickly, about 8 minutes for the block of cases, so all-in I'm at about 26 minutes to charge and load 50 rounds.

I do it by only weighing the powder charge once and then counting kernels to hit the desired target weight. I've found through repeated double checking that Varget is 0.02 per kernel and can be reliably counted out at 5 kernels per 0.1g, up to about ~10 kernels at which point it pushes the charge weight an extra 0.02 over. You can do this with other powders too by figuring out their average per kernel weight. Having a powder with a consistent kernel size is a plus, but even if there is some variation in kernel size the fact that you use an average weight across kernels then add multiple kernels at a time averages things out.

The workflow goes like this....

1) Drop powder into pan from thrower while glancing at empty scale to confirm the negative pan weight number has not changed. (This helps you catch scale drift immediately)
2) Put full powder pan on scale
3) While scale is in process of registering the weight, move the funnel to the next empty case in the block
4) View powder weight, thrown between 0.04 and 0.2g low usually. Do the mental math as to how many kernels are missing.
5) From the pile of loose kernels on top of the raised workbench, use a straight edge to cut/count out the desired number of kernels.
6) Push the kernels off the edge of the platform straight into the powder pan, held flush underneath the counter edge by my other hand.
7) Dump completed powder charge into waiting funnel.
<repeat process>

If I get an overthrow of up to 3 or 4 kernels I'll pull them out with tweezers, I can do that pretty fast. Any more of an overthrow than that I'll just dump it back in the powder thrower and throw a new charge. If I've had to add more than a dozen kernels or so I'll recheck the weight to make sure it hasn't gone off by 0.02gr.

I've got an Omega trickler right there but this new method is much faster. The GemPro isn't very responsive to trickling in one or two kernels so you'd have to jostle the pan and wait for it to register the new weight. Plus, through repeated double checking I've found that counting kernels is very accurate and there's no need to re-weigh the charge a second time. I would always struggle with staring closely at the trickler spout trying to count how many kernels came out and if I'd gotten a double kernel dumped in or not. Simply counting them all at once is much easier.

Here's a picture of what the reloading setup looks like which should help clarify everything above. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/img.photobucket.com\/albums\/v483\/sheldonnalos\/_MG_5500_zpseeveh7qc.jpg"}[/IMG2]








And here's a link to a video of the workflow in action.




















5 cased loaded, 15 seconds per case average.

The process is faster and more accurate than a Chargemaster, all these charge weights are within one kernel of powder of target weight. I've double checked MANY times. Not the only way to skin a cat and there are certainly nicer tools available. I just wish I'd had someone show me this method earlier. Could have skipped buying a couple different tricklers. Could have saved a LOT of time compared to how I was loading before.
 
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Very good!

Years ago, I too abandoned my trickler. Started throwing then grabbing kernels and going instinctive on feel of the amount of powder to pinch and put in the pan on my oldy but goody Scott Parker tuned Lyman. I get pretty fast but your way is faster yet.

I go to the kernel as well but suffer an extra here and there.

I suppose e scales are getting better as every year goes by. The older ones I had broke or drifted like crazy.
 
Yeah, I've got a Scott Parker tuned scale as well, but based on my testing I can hold closer tolerances with the GemPro than I can with the beam. The GemPro still drifts from time to time, but I'm able to catch it immediately because I watch the negative number on the scale when I lift the pan. As soon as it changes 0.02 I set the empty pan back on the scale and it does some sort of auto rezero. Sometimes the drift happens every 10-15 rounds, sometimes not at all. The other thing I have is a home made check weight that I use every loading session. It's just a stainless steel screw filed down until it reads 45 grains. I pull it out every time I'm loading, and will weigh it anytime I see drift and rezero to make sure the calibration isn't off. So far it's weighed the same amount every loading session.

Ultimately I don't think that weighing to the kernel is particularly necessary. If you've selected a charge weight in the middle of a node (ie OCW load development) then +/- 0.1g isn't going to affect you much and a Chargemaster or similar would be fine and you won't see the difference on target in a significant fashion. I just like this because 1) the GemPro is cheap, half the cost of a Chargemaster and 2) It feeds my OCD tendencies and I don't have to worry about whether the loads I made are lacking in some fashion and 3) It goes pretty quickly all things considered.

On the flip side, I'm moving towards just throwing practice ammo on the Dillon 550 and being okay with the slight variation in charge weights. And on the other end of the spectrum it wouldn't surprise me if I ended up with an FX120i and Autotrickler combo someday. :)
 
Nice. I am using 4064 for my 308, I will have to see if I can find a average. I want to say .02 also but some kernels are really short and some are really long. Might just need to filter those out of the pile and put them back into the hopper.
 
I love my GemPro. I throw with a Chargemaster then dump it on the GemPro and I adjust with the tweezers that came with the scale. It's usually
only a couple kernels here or there so it's not that bad. Varget here as well so that .02 per kernel is spot on.


Sent from my iPhone using Tapatalk
 
That moment - with palm smacked squarely on forehead - when you think, 'Why didn't I think of that!?'

I've got 30 pieces of .308 brass waiting for a charge and a bullet waiting on the bench. I'm going to try this when I get a chance to load them (hopefully today). If this works and I'm able to shelve the trickler, it will save much time and tedium from the reloading process.

Thanks for the tip!

UPDATE: I had a chance to load those 30 pieces this afternoon, and even after taking the time to double-check the weight after dropping my kernels in, it was quite a bit faster, and even seemed simpler and more streamlined. Once I trust myself enough to stop double-checking it will be that much quicker of a process. Very glad for this thread.
 
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Yeah, I've got a Scott Parker tuned scale as well, but based on my testing I can hold closer tolerances with the GemPro than I can with the beam. The GemPro still drifts from time to time, but I'm able to catch it immediately because I watch the negative number on the scale when I lift the pan. As soon as it changes 0.02 I set the empty pan back on the scale and it does some sort of auto rezero. Sometimes the drift happens every 10-15 rounds, sometimes not at all. The other thing I have is a home made check weight that I use every loading session. It's just a stainless steel screw filed down until it reads 45 grains. I pull it out every time I'm loading, and will weigh it anytime I see drift and rezero to make sure the calibration isn't off. So far it's weighed the same amount every loading session.

Ultimately I don't think that weighing to the kernel is particularly necessary. If you've selected a charge weight in the middle of a node (ie OCW load development) then +/- 0.1g isn't going to affect you much and a Chargemaster or similar would be fine and you won't see the difference on target in a significant fashion. I just like this because 1) the GemPro is cheap, half the cost of a Chargemaster and 2) It feeds my OCD tendencies and I don't have to worry about whether the loads I made are lacking in some fashion and 3) It goes pretty quickly all things considered.

On the flip side, I'm moving towards just throwing practice ammo on the Dillon 550 and being okay with the slight variation in charge weights. And on the other end of the spectrum it wouldn't surprise me if I ended up with an FX120i and Autotrickler combo someday. :)


Yeah, the tuned beam scale isn't perfect and needs the beam centered once in while.

Well, I like options and it's good that people post stuff like this so others can be informed about new faster ways to do things.



 
Thats a cool looking reloading box you have there. Do you have the dimensions? I am thinking of making something similar myself.
 
That's some good info mate, I'll be making myself one of those little reloading boxes.
 
Sheldon N I believe I read in a previous thread that you couldn't recommend the GemPro250 due to some shortcomings. My cheap FA DS-750 is drifting all over the place so I am trying to decide between a GemPro250 and a new (old stock) rcbs 10-10 built by ohaus. Would you recommend the GemPro250?
 
I've played with a gempro a bit. I was weighing close on chargemaster, moving to gempro and trying to top off with trickler. Quickly learned trickler wasn't worth the trouble and proceeded to hand picking kernals.

I really like what you're doing here... and I really like the rcbs competition thrower.

Now i'm considering the rcbs comp thrower and A&D scale. Gempro is accurate but was a bit quirky for my taste (you've proved it's efficient, guess I should suck it up and skip A&D)


But I usually get hung up on diminishing returns.... checking chargemaster with gempro, the chargemaster is truly accurate to 0.2 gr. ~+/- 20 fps?

Eh I don't know... loading straight off the chargemaster tac rifle has done dang near 1/2 MOA at 1000 (5.656, 5 shot). If I don't suck it can hold 1 MOA all day long at 1K.

You true bench resters (cheating, crazy people ;):p) probably feel different. Part of me strives for perfection, and part of me wonders if chargemaster does just fine for my tactical rifles.

Thanks for the informative, interesting post.
 
Sheldon N I believe I read in a previous thread that you couldn't recommend the GemPro250 due to some shortcomings. My cheap FA DS-750 is drifting all over the place so I am trying to decide between a GemPro250 and a new (old stock) rcbs 10-10 built by ohaus. Would you recommend the GemPro250?

The gem 250 doesnt respond well to trickling. So each trickle will require you pressing down on or picking up on the pan. The scale tries to stick with one number to resist drifting so any tiny little inputs are ignored until its too much and by that point you have over trickled unless you disturb the pan and prompt it for a fresh reading every kernel or two. Though some people have become accustomed to it and it doesnt bother them. Its just what your expectations and wants are.

If I had to make the choice between a nonautomated electronic scale or a beam based off of well, generalities, I would probably take the beam so long as I had a way to get it high enough to my eye so Im not breaking my back to get my eye level to it. I currently move everything to a small table in front of a couch and TV. I used to have a little rcbs 5-10 and it killed me stooped over to get coffee table level. My charge master has a digital display thats angled up at a 45 or something and I can sit comfortably on the couch straight up and see the read out fine. Not only has it eliminated the necessity of me being actively weighing my stuff it has saved me contorting myself to use the thing. Since I cant get a beam up high enough though I would go gempro250 due to my laziness.

I tried that frankford 750 too between the 5-10 and the CM and it was a pain. I spent more time going between the beam and that little thing trying to double check one or the other. The beam was consistent but slow, that 750 thing was always either .1 high or .1 low but never the same way and it, like the 250, didnt like trickling or small incremental additions without being distrubed/reprompted.

Honestly upgrading from the 750 there is no wrong choice.
 
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Hey guys, I'm glad that you're finding this info helpful. To answer the questions about the reloading box....

The box is 21" wide, 8" deep on the top and 11" deep at the bottom, 12 1/2" tall. The top and bottom are pretty thick, 1 1/4" solid walnut, the sides are 3/4" thick, and the back is thin 1/8" plywood. It's screwed to the top of my workbench and is super solid, no flex at all. If you want to run a RCBS Rockchucker on it you need an extra 3/4" of height for the handle to clear the top of the workbench at the bottom of the stroke, total height needed is 13 1/4". I get that by having the box sitting on a piece of 3/4" MDF. I actually screwed the box to the MDF from underneath, then screwed the MDF down onto the workbench so there are no visible screws in the box.

As to my prior comments (maybe a year ago?) about choosing another scale over the GemPro, I believe that was back when I was trying to trickle up to my charge weight using a Omega trickler. That was an exercise in frustration. if you want to trickle, the GemPro is not the ideal choice. You'll have to jostle the pan every time as noted above.However, since settling on this new kernel counting method I'm a huge fan of the GemPro. The technique plays perfectly into the strengths of the scale - static weighing.

On the subject of drift and accuracy, I see drift with my GemPro250 as well. The thing I like about this method is that you can immediately spot drift and control it, as well as ensure load consistency from session to session. The things I do to help the process are...

1) Basic scale technique stuff. Leave the scale on/warmed up. Make sure it's level. No electronics in the area. LED light overhead vs fluorescent. Make sure I place the load on the scale evenly in the center of the pan every time. Keep room temp consistent, temp swings will cause drift. No drafts in the area.

2) Do a few "test" weighs when I start. Usually the first one or two may be off a tiny bit, then it settles into accurate readings.

3) Have known reference object weights. I know my scale pan should read 141.56gr and I've got a stainless screw that weighs 45.02gr. I pull that screw out every loading session and check it for reference, and I will also check it anytime I rezero the scale. It's always been on and I don't think I've had to calibrate the scale in the last 1000 rounds.

4) Control for drift by watching the negative pan weight when you lift the pan off the scale. This one is the key to the workflow. If my scale starts to read -141.58 instead of -141.56 I know that I've got 0.02 of drift and I need to retare the scale. What's cool is that the GemPro has some sort of "auto zero" feature so if you put the empty pan on the scale and wait for it to read 0.00 again it will reset the zero and when you lift the pan again it will read -141.56 again. No need to hit the tare button. Sometimes I'll double check at that point with my stainless screw check weight. Personally, I experience this need to set down the empty pan on the scale to "re-tare" a few times a loading session. Sometimes it's every 5 rounds, sometimes I'll go 30-40 in a row with consistent readings and no drift. The "re-tare" only adds about 10 seconds so I don't mind it. Having the check weight gives me peace of mind that the loads I weighed at the beginning of the session are the same as the ones at the end of the session.


Now on the subject of beam scales and trickling vs a GemPro250. I've got a Scott Parker tuned beam scale, it's really nice and I know for sure that it's calibrated and is not going to drift. The weights match my GemPro250 as well as known reference weights like a bullet. It is sensitive to the kernel, I can see the beam move when I add just one kernel of powder and I've got it up near eye level.

I tested myself using my Omega trickler and doing my absolute best to hit the target weight perfectly with the beam. I weighed out 10 charges and then cross checked them on the GemPro alongside the check weight to make sure I had a consistent reference. What I found was that I personally could not hold as tight of a tolerance with the beam scale as I could with the GemPro, and it was several orders of magnitude slower. I'll be the first to admit that it's probably me as the user and not the scale, but for my purposes I couldn't see myself loading that way in regular practice. Now I'm definitely NOT selling the beam scale, since I'm sure the GemPro will crap out on me at the worst possible time and I'll need to load some ammo. The GemPro is cheap Chinese made junk after all, let's not kid ourselves. :)

Realistically I'm confident that my loads are coming out +/- within 0.02gr of my target weight even with kernel counting and not reweighing, and that I"m not getting more than +/-0.02gr of drift. You could tighten that up and slow the process a bit by taking the time to reweigh the final load vs trusting your initial weight and how many kernels you added. After doing this a bunch, I'm staying very consistent at sub 20 min to load a block of 50 cases.

The question of whether you need to weigh this precise is a totally different issue. With a good load at the right node for your rifle the answer is probably not. Chargemaster or heck even a Dillon thrower with the right powder that meters well is probably fine. What I like about this process is that the equipment is cheap ($120 vs $275 for a Chargemaster), it's a well controlled process for the pitfalls of digital scales and drift, and it's fast and efficient. What's probably best is if you can use this process and combine it with the healthy perspective that full blown OCD isn't necessarily needed. You can ask yourself... Do I need to reweigh this charge a second time to see if the 8 kernels I added got me to 41.80 gr? Do I really need to grab the tweezers and pull out that kernel or is 41.82 okay?

I'm still not sure which side of me is winning that battle though. :)
 
I use a big magnifying Loupe, with a light in it, attached to the bench, about 6" away from the pointer on my Scott Parker tuned beam scale.The magnified image is huge and well lit so seeing the one kernel difference is easy! With my ultrasonic cleaner lifting the scale to eye level (yeah, funny I know, but I don't use the cleaner much) It's perfectly placed and I'm in a comfy office chair so my setup is as ideal as it gets.



 
I'm still not sure which side of me is winning that battle though. :)

My exact problem... one day i'm ordering concentricicty gauges, the next I'm wondering if it really makes my groups better.... curiosity killed the cat (and wallet) haha

 
I use a big magnifying Loupe, with a light in it, attached to the bench, about 6" away from the pointer on my Scott Parker tuned beam scale.The magnified image is huge and well lit so seeing the one kernel difference is easy! With my ultrasonic cleaner lifting the scale to eye level (yeah, funny I know, but I don't use the cleaner much) It's perfectly placed and I'm in a comfy office chair so my setup is as ideal as it gets.
The other thing you can do it aim a camera at the pointer, which eliminates parallax error. You could even just use your cell phone camera and prop it up so it's looking right at the pointer
 
I love my GemPro. I throw with a Chargemaster then dump it on the GemPro and I adjust with the tweezers that came with the scale. It's usually
only a couple kernels here or there so it's not that bad. Varget here as well so that .02 per kernel is spot on.


Sent from my iPhone using Tapatalk

This is what I'm doing. Stumbled into it when my CM was acting up, prior to sending it in for replacement. While my CM was gone I borrowed a Lyman Gen6 from a buddy and found it was accurate within .02gr about 80% of the time and within .06 the other 20% of the time. When my new CM arrived it's only accurate within .02gr about 60% of the time and it's off by .14gr at least 30% of the time. I'm pretty disappointed in my CM and I'm thinking about getting a Lyman Gen 6 to replace it.

I'm in love with my Gempro 250, though! I've found that each kernel of H4350 weighs .02gr. Just like the OP, I do some quick math on the number of kernels to get my charge weight dead-on and I trickle or pull them. I DO, usually, wait on the Gempro and double check the final weight. It takes about 4-5 seconds for a kernel or two to register. It's not the fastest way to load but my ES and SD really show the benefits of this level of precision. I'm into shooting bugholes so it's worth it to me. Recently I've gotten a Savage 10/110 Predator that's bone stock to shoot consistently right around .3" (+\- .04) at 100 and sub 1" at 300. ES in the single digits usually. This would not be possible without precise charge weights that the Gempro can produce.

Great thread! I thought I was the only one OCD enough with my loading to do this!!! Lmao!


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The other thing you can do it aim a camera at the pointer, which eliminates parallax error. You could even just use your cell phone camera and prop it up so it's looking right at the pointer

Yeah, I've seen those methods on youtube and the use of a computer monitor too. You know I'm a cheap ass because of the ultrasonic, lol. Old eyes really need that bright and big magnifier which I got for free.
 
I just a couple of Lymans side by side to charge 100 at a time. They are about +/- .01 of the target weight. Like mentioned have to make sure pan returns to zero but are pretty good about having to zero at a minimum. I use a Lee scoop to speed it up a little. Takes about 30 to 45 minutes.

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"I DO, usually, wait on the Gempro and double check the final weight. It takes about 4-5 seconds for a kernel or two to register."

Just tap the platen edge with your pick-ups to get the GemPro to reweigh the charge after dropping a kernel or two. Faster and better.

RMD
 
Thanks for posting this info.. I kind of thought I needed to spend $1,200 bucks to get a scale that accurate.. so I'll have a Gem Pro here on Tuesday.
 
I noticed something I don't understand in the GemPro 250 manual. On page 4, in the Features section, the manual reads,

"Adjustable Accuracy (only on GemPro 250)
The GemPro250 has two Carat modes. One reads in 0.001g/0.005ct increments and the other reads to 0.002g/0.01ct. This was done so that jewelers can choose which accuracy they require for their use. We suggest to use 0.002/0.01ct when possible for maximum accuracy."

This doesn't make sense to me. I would think that the 0.001g mode would be finer in its measurements than 0.002g. I initially thought this might be a typo, but it appears, word for word again on page 5 in the Key Pad Functions section. Does anyone know what their logic is in recommending a coarser measurement mode for achieving "maximum accuracy"?



 
I'm going to try this. I've been scooping my H1000 out of a pyrex bowl with a measuring spoon and dumping onto an RCBS Rangemaster 750 then trickling up to weight. Terribly slow. Went with the spoon because my RCBS thrower was not throwing a consistent charge. Seemed to hang up periodically, etc. Is the stick powder the problem? BTW, I was using the insert to keep powder from clogging up the bottom. Do I need to upgrade to the comp model to get a relatively accurate throw?

Also, any hints on speeding up brass prep? Trimming seems to eat up most of my time.

Finally, Hornady bullets rock. Don't have the numbers, but my set up is holding half minute-is at 750y with 15.5MOA come up. Too bad it takes forever the way I'm doing it now.

Thanks and

God bless America
 
I am going to try this with my practice ammo to start. I have had a gem pro 250 for two years. Currently I use a lily dandy electric trickler and a Redding tickler because my powder measure doesn’t like extruded powder. I am currently looking at the Lyman to speed up. So I lose time because sometimes I have to trickler as much as .8 grains and then lift then electric trickle. I agree with everything your saying about the gem pro. It’s a good scale you just have figure yours out if you buy one. Another thing on about the gem pro I have found is if you trickle up and wait the 3 sec for the scale to auto weigh. Their is a difference in measured powder between trickling up and stopping, lifting the pan to get the scale to recheck the weight. We are talking .02 grains but it is definitely there on mine. I will disagree with one thing your mention. Varget kernels weigh .02, .03, .04, .05 the gem pro can only measure in even increments at .02, .04 so sometimes your gonna miss this is what drives me crazy. When I read what your saying practically your 100% correct this .01 to .03 variance likely doesn’t matter for practical accuracy at PRS event. I would bet there is more variation in the shooter than can be seen by this powder variance. Another thing is that a bonus with buying the Lyman is the 50 gram check weight because the gem pro needs the 20 and 50 gram check weights to do a linear zero. I have never done this because I refused to get fleeced for a 50 gram check weight I just rezero with the 20 gram that came with the gem pro. My rifle ammo is currently all single digit sd at max load data so the gem pro can produce good ammo.
 
I will disagree with one thing your mention. Varget kernels weigh .02, .03, .04, .05 the gem pro can only measure in even increments at .02, .04 so sometimes your gonna miss this is what drives me crazy.

I've not run into that kind of variation in Varget with the lots that I've used. The 0.02gr per kernel has worked extremely well for me over thousands of match rounds loaded. I've checked and double checked the final weights so many times and it's solid. You might see an overall charge go a kernel high or a kernel low, but that's within the accuracy range of the scale. 5 kernels per 0.1 grain, 10 for 0.2, maybe subtract one kernel once you get beyond 0.2gr off the target charge weight.

FWIW, I sold my GemPro and got an A&D FX120i scale. Have used the same method with it with the same results. Will probably get an auto-trickler sometime, but currently am borrowing a friends Prometheus... so not much incentive to do anything other than enjoy that for now. :)
 
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