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Old November 13, 2012, 01:52 PM   #1
iraiam
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auto ammunition scale: would you buy one?

I made a stand alone "semi-auto" amuunition scale that I use. i built it mainly for myself, but I may try and sell the design.

I quickly weigh each round before it gets put into an ammunition box either for a range trip or long term storage, the scale is sensitive enough that it will detect, no powder, double powder charge, no primer. In fact it will detect even small differences in weight, say from a different brand of case, or an incorrect powder charge.

It is targeted at the reloader who produces large quantities or large batches of ammunition. (like me)

The only problem is due to the cost of the parts in this thing, it would probably cost about $500 retail, I don't know how marketable it would be, considering that most reloaders are in it to save money.
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Last edited by iraiam; November 13, 2012 at 01:58 PM.
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Old November 13, 2012, 01:54 PM   #2
temmi
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I already weigh each round

But

I am not a Volume kinda guy

100 at a time on a single stage

Snake
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Old November 13, 2012, 02:00 PM   #3
iraiam
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Quote:
I already weigh each round
Yes, me too, but it got rather tedious loading batches of 500-1000 every 1-2 weeks.
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Old November 13, 2012, 07:30 PM   #4
Catfish
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You need to keep your old scales and get yourself a 550 Dillon press.
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Old November 13, 2012, 07:41 PM   #5
Brian Pfleuger
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Not unless it does something important that's not obvious and that any ordinary digital scale won't do. I can't imagine what that would be.
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Old November 13, 2012, 09:33 PM   #6
wncchester
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It's not for me. I know cases easily vary enough to screw up many cartridge readings and I have a better, faster and cheeper way of confirming high, low or missed powder charges anyway - I look in every case, every time I reload.
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Old November 13, 2012, 10:07 PM   #7
jmorris
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Pepole are visual, need eye candy to get excited. Have any photos or a video or your device in action?
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Old November 13, 2012, 10:25 PM   #8
higgite
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To answer your question.... no. When loading bulk, I use three powder cops to warn me of no powder charge or double charge. A die on the press plus my two eyeballs.

And powder all over the press, the bench and the floor tells me when a primer is missing long before a scale would. Don't ask me how I know that.
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Old November 14, 2012, 12:18 AM   #9
warningshot
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Free market advise right here.

Five hundred? Did you say, fff...ffii..fiivvv...hundred!?

The trend is going back towards simplicity and bottom line cost. I don't think speed & quanity will be the big reloading issue tomorrow as it was yesterday.
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Old November 14, 2012, 04:28 AM   #10
Etkini
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$500? A Hornady Auto-Charge is about $225, and an RCBS Chargemaster is about $300.. You'd be competing in a market that's, in my opinion, not really there.

Not trying to put you down at all, but with a good powder thrower running about $100 and a good beam scale running a bit less, I can't see any but the most hardcore spending $500 - and if they do it's probably on a Prometheus.

I am interested in how it works from an engineering stand point though, I love seeing ingenuity.
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Old November 14, 2012, 09:38 AM   #11
jmorris
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I don't think he is talking about an auto powder drop. Not sure, why I asked for photo/video but when I think auto ammo scale that could detect small differences in weight I am thinking "brass sorter". Many folks would be interested in that.
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Old November 14, 2012, 10:10 AM   #12
Brian Pfleuger
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^^^

Yeah, he's talking about variance in finished rounds. That works fine if you're using benchrest quality components and powder dispensed by weight but it doesn't work for bulk brass, volumetric powder and "ordinary" or bulk bullets.

I load Norma brass, CCI BR primers, Barnes bullets and powder dispensed by an RCBS AutoCharge and still get variances up to 1.0gr.

Bulk stuff, with powder dispensed by volume, would be impossible.
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Last edited by Brian Pfleuger; November 14, 2012 at 12:52 PM. Reason: spelling
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Old November 14, 2012, 12:49 PM   #13
Etkini
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Ah, I just re-read the post and now I get it. But then that brings this:

You should be able to tell if there's no primer, either by checking them or when the powder flies out the flash hole and plugs up your press.

Each component has variances within themselves, similar to what Brian stated. My .308 cases have variances of over 5g between each one. Bullets are fairly consistent, but I have noticed .5-1gr difference between bullets in some of the bulk .223 and .40S&W I've bought. I think you'd have to figure out what's an acceptable variance to let slide, but at that point weighing finished ammo is probably a waste of time anyway.

Then again, maybe you have a system that works really well. I'd still love to see it.
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Old November 14, 2012, 01:18 PM   #14
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Given all the electronic scales already on the market are getting cheaper, all I can think is that he is talking about a high speed weighing system. These are used in industry. The problems with this application, however, have already been mentioned, and that is multiple competing overlapping error sources. I might have, say, a .45 Auto case that weighs 3 grains less than another. If that same case happens to have 3 grains too much powder, then the finished cartridge will look perfectly good on a scale but actually be dangerous.

As far as selecting cartridges for accuracy, there's is a statistical problem. Let's suppose your cases have 3 grains extreme spread. The standard deviation will then be in the range of 1 grain. Further suppose you have a powder measure that throws the charge to an extreme spread of 0.6 grains. It will have a standard deviation not far from 0.2 grains. Standard deviation interrelation adds as the square root of the sum of the squares, so the net cartridge standard deviation from these two factors will be the square root of 1²+0.2² or √1+.04=1.02. That's not much different from the case weight SD alone. So you could have the weight look pretty close to normal for the case brass spread when the powder is actually varying all over its extremes. In other words, the case weight variation will interact such that it will cover up all but really gross charge weight deviations most of the time. So weighing finished cartridges as an accuracy selection strategy won't likely work, and accuracy freaks are the main market for expensive tools.

As far as weighing for safety rather than accuracy, primers all weigh about 5 grains, and good brands of bullets are very consistent. But the only way you could detect a safe load vs. and unsafe load or even a missing primer is going to be to pre-weigh each case and keep track of that case through loading to isolate the powder weight as a variable.
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Old November 14, 2012, 03:54 PM   #15
bullspotter
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By weight alone, on pistol ammo, this pry wont work. I work for a comercial. reloader and we had a press malufunction, had to replace some parts, in the process, a round didnt get a powder charge and fell into the try with the finished rounds. Crap, off to the scale, we weighed every one and pulled the 10 lightest rounds just knowing it was one of those 10. no such luck. Got about half weigh though the box of about 125 rounds when we found it, got to like the hammer pullers....... We were loading 45 acp, mixed brass with a 230 grain precision delta bullet.

Their normaly is not enough consitancy in weights of pistol rounds to find a over or under charge, and sometimes no charge even, as far as missing primers, i see those right away as they leave a trail of powder under them every where they go........
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Old November 14, 2012, 07:59 PM   #16
jmorris
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Quote:
The problems with this application, however, have already been mentioned, and that is multiple competing overlapping error sources. I might have, say, a .45 Auto case that weighs 3 grains less than another. If that same case happens to have 3 grains too much powder, then the finished cartridge will look perfectly good on a scale but actually be dangerous.
Yes, but if you are a long range rifle shooter and could sort buckets of empty cases by weight without touching one or a pistol shooter that could sort mixed brass into caliber (or better) there is money to be made.

For example the machines that Camdex and Scharch make only sort by diameter and cost over $7000.
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Old November 14, 2012, 09:13 PM   #17
wncchester
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For example the machines that Camdex and Scharch make only sort by diameter and cost over $7000.

Wonder how many of those they sell in an average week.
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Old November 14, 2012, 11:09 PM   #18
jmorris
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Quote:

Wonder how many of those they sell in an average week.
A hell of a lot more if they were only $500.
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