Precision Digital Scale

aheppner

aheppner

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hey, i'm looking for a precision scale to buy myself for christmas....

I'm using an RCBS beam scale right now, it works well but I think I could be more consistant with a little more precision.

I mostly load .223 so I throw charges with my lyman measure (always set the same) into the scale pan. Sometimes after zeroing the scale I find I have to trickle every charge quite a bit and then another day I'm throwing charges that are over weight. I would say that all of my charges are within .1 gr for any givin loading session but from session to session I have no idea how much variation there could be.

anyway enough of my life story.....

im looking to tighten my tolerance to less than .1gr if I can because i've read that small cases like .223 require very consistantly measured powder. makes sense the smaller the case the more a givin variation will affect velocity/pressure



what are you guys using for scales?

Gem Pro 250s? or something else?
 
Contact Jerry at Mystic Precision for his 2 cents worth. He's a competitive shooter, shoots beyond 1000 yds. and really knows his stuff. He use to use a GEM Pro 250 but uses something else now. (I've got the 250 and really like it, weighs to .02 gr.) Jerry is a site sponsor at the top of the page. Best of luck
 
BB, thanks for the referal.

I have been using the Gempro for a while but it does drift and get be real fussy about home electrical noise.

I am now using the FX-120i. Far more stable. Fast, and precise. Also, 2.5 times the cost. You can load with either to 0.02gr of powder and that is important for peak 223 LR performance.

That is 1 kernel of Varget.

Jerry
 
thanks Big Boar and Jerry

I think I'll give the GemPro a try then, right now I can't justify spending more $ than that.


Jerry can you elaborate a little bit on the electrical noise issue and drift?

I realize that any air movement can cause inacurate readings but can't the drift be eliminated by zeroing the scale before each use or even every 50 rounds?
 
Cambridge enviro, fx-120i $525 and in Canada, they were $400ea when I got mine. Add tax and a few dollars for shipping, keep in mind its a real scale, not a reloading market plastic toy.

They are indeed nearly double in the US.
 
It sounds like the gem pro should get it done and the fx120i is for serious competitors.

Since i don't compete and have a long list of other firearms related goodies i need i think the gem pro takes this one.

Next after that is a decent range finder.
 
I use the RCBS Chargmaster 1500. I always use the RCBS 5-0-5 beam arm scale as a second check on every charge. I learned today that the electronic scale must be dead level and aligned with a bubble level or it will not throw an accurate charge every time. It can be off as much as .1 -.7 grains if not dead level.
 
TedNugent said:
Ouch! For that kind of coin look for an rcbs chargemaster 1500.
Think I got mine in the US for under 350 shipped.
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Listen to Jerry on this one - I didn't and got burned.

The chargemaster is great (enough) for throwing approximate charges.... it's essentially an electronic powder thrower, and no more.

I weighed what the chargemaster threw on my gempro 250 just to see, and it was generally within tolerance (it is +/- 0.1 grains) but it wasn't nearly dead on. I was able to get *slightly* better results with the chargemaster by having it throw 0.1 under, then trickling up JUST until the number rolled over to the number I wanted. But even then, it was regularly off by an amount I'd consider to be significant when loading especially for .223 or other small cartridges.

The Gempro is alright, but like Jerry says, it can drift and it doesn't like electronic/electromagnetic noise. I ended up putting TWO ferrite beads on my power cord, four capacitors (one and two respectively on each end of the cord), total overkill, but now I know that the supply line is as filtered as it can get. I used two 1000uF caps, one on either side of the ferrite bead, to create a Pi filter. Not sure the cutoff frequency, but it should kill most of the noise that is present. I ended up taking it a step farther as I have a lab grade DC power supply, so I hooked it up to that instead of the factory plug. It certainly works better, but not perfect.

I also took the scale apart and sprayed some (not much) anti-static spray on the inside, let it evaporate, sprayed the pan and pan support (wiped these down after while they were still wet with a paper towel, which isn't ideal but i didn't want any residue on the pan). This helped probably more than anything. I still double check with the cal weight after every 3-5 rounds though, and it usually needs to be re-tared within 6-10 rounds.

I'm going to be in the market for the 120i pretty soon here I think. I do have a second gempro coming, as the first one is being replaced free of charge, so we'll see how it works. if it ends up being repeatable and reliable enough, then I may forgo a new scale, otherwise these will be sold (as they function fine as far as a gempro is concerned, they just don't seem to be up to the task I WANT them to be - it's the nature of any strain gauge based scale though) and the FX-120i will be in the mail.

Another option is contacting Scott Parker (accurate shooter forums I think) and getting a tuned up beam scale from him. he can get a good beam scale to show one grain of varget, though my preference is towards a good electronic scale just because it is faster, I think.
 
Forcedair said:
Me too! We're probably not the only ones.
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They are better than people give them credit for! If you clean up and sharpen the knife edges, clean up and smooth the place where the knife edges rest, put a sewing needle on the end of the beam and rebalance it using a good set of weights, then they can be impressive.

Also might be worth using a set of weights to ensure that each of the spots for a given weight is actually correct - they can be slightly off. no big deal for repeatability, but if you want to take a charge weight from that scale and use it on another, you'll want it to be not only precise but accurate.
 
I'm still looking at getting a GemPro but I have one more question.

krprice mentioned using a "lab grade DC power supply" because the ac adaptor causes electrical interference,

can't this be solved by using batteries in the scale, batteries are DC therefor no interference?
 
Yes, that can certainly solve it. But then you have to change them regularly as when they start getting low then you're running into issues with precision again.

Best solution is to use either a lab power supply (big money, I just happened to have one) or at least use a filtering setup on the power wire.

I'm going to be selling my gempro since I just bought a Sartorius analytical balance, accurate to 0.0015 grains/0.1mg.

If you're interested, 70gr would come with the filter set up on the power wire already.
Pm me if you're interested otherwise it's going on the ee in a few days
 
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