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Old September 15, 2011, 10:18 AM   #1
GregInAtl
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Scale Verification

I noticed that my RCBS 505 beam did not yield the same results as the RCBS 750 digital scale (which I am returning to Cabelas for other reasons). I used the check weight from the 750 to determine that I need to raise the support leg on the 505 beam scale. Once I did that, they both yield the same result. Once I don't have the 750 anymore, I won't have anyway to determine if it needs adjusted and by how much. Where can I get a cheap check weight or something else to use that is effective. RCBS sells a check weight set but it cost about $35, almost half the cost of the 505
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Old September 15, 2011, 10:41 AM   #2
Habaz72
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Can you use the check weight now to calibrate the scale before you return the item then find something else around the house and weigh it then record that weight and use it as a new check weight?

Edit: Or you can weigh a projectile, they have a known weight in grains.
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Old September 15, 2011, 11:05 AM   #3
Jim Watson
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I have a fired large pistol primer and a nominal 45 grain bullet which the freshly calibrated PACT and the Lyman balance agree to weigh 4.2 and 44.9 grains, respectively. I use them for check weights and recalibrate when necessary. The primer was free and the bullet cost about a dime.
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Old September 15, 2011, 11:19 AM   #4
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Next time you're at Lowe's or a hardware, get a roll of bare stainless steel wire. Make a little roll of it around your fingers and trim it to match the check weight on the scale.

Once you have that, you can go it one better by going to a compounding pharmacy (one that mixes some prescriptions from scratch), which will have an annually calibrated scale with 0.001 gram (0.015432 grain) resolution and can weigh the stainless wad for you. The result will be in grams, but multiply the gram result by 15.432 to get the number of grains. That will get you a still better read.
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Old September 15, 2011, 11:40 AM   #5
Gary Wells
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A dime weighs exactly 35 grs.
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Old September 15, 2011, 11:41 AM   #6
cdoc42
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After checking my RCBS digital scale with pharmaceutical grade apothecary weights, and zeroing the pan that weighed 99.3 grains, I found the following weights:

One cent = 38.4 gr
5 cents = 76.2 gr
10 cents= 34.9 gr
25 cents = 86.8 gr.

There are times I find the weights are off by (+) or (-) 0.1gr because the scale zero vacillates to 99.4 or 99.2 which I think is a reflection of electrical current more than air current.

You may want to weigh the coins to see how close you are. If you are too far off, you'll need to buy a set of known weights or ask a pharmacist if he/she has a few extras that are not needed.
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Old September 15, 2011, 11:46 AM   #7
Mike Irwin
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Yep, US coins are more than exact enough to be used as check weights.

This US Mint page shows the weight of current coins in GRAMS. You have to convert the gram weight to grains using google.

http://www.usmint.gov/about_the_mint...specifications
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Old September 15, 2011, 12:01 PM   #8
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I did similar to UncleNick. I used a piece of aluminum rod and cut it to length. I cut it slightly long and then filed it until it was the weight I wanted.
Aluminum being light gives you a larger piece to handle and keep track of.
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Old September 15, 2011, 02:48 PM   #9
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Question; why do you think it's not the digital that's off?

I've never seen a beam scale off more than a tenth or so and that's meaningless.
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Old September 15, 2011, 03:05 PM   #10
GregInAtl
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The digital comes with 2 check weights, one 20grams and another 30grams. The digital registers the exact weight of each of them when I place them on the scale. Also, the beam is off by a couple tenths of a grain when I place the check weight on the beam. A couple of 10ths could be a big deal if the minimum is 5.2 and the max is 5.8 in the load manual. I can correct it by adjusting the leg on that front of the scale but if I don't have a check weight anymore (after I return the digital) I won't know how much to adjust. I can use a coin or something as mentioned above.
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Old September 15, 2011, 03:33 PM   #11
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I favor the idea of cutting a piece of wire, or several pieces of wire in different lengths and then taking them to the pharmacy or jeweler and getting them to weigh it for you and keep that as your standard. One time out of curiosity I weighed several dimes. I actually saw variations of over 0.2 gr. That is too m uch for a lot of us.
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Old September 15, 2011, 03:56 PM   #12
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Adjusting the support leg is not the way to balance the beam. What you want to do is set it for zero then put a known weight on it and then add shot to the pan until you are measuring the correct weight. You then add this to the pan holder. If you unscrew the pan holder you will find adjustment weights inside. You can add or remove from the pan holder.
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Old September 15, 2011, 03:57 PM   #13
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I just purchased this calibration set - it's currently around $11.

http://www.amazon.com/gp/product/B003STEJAC

I haven't used it yet, but it should do the job.
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Old September 15, 2011, 04:02 PM   #14
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I hate to burst bubbles on coins, but when this came up a couple of years ago on another forum I took a lab scale and weighed randomly selected quarters. The results were:

35 quarters in total:

Mean (average) weight:
87.62 grains

Highest:
89.02 grains

Lowest:
85.70 grains

Extreme Spread:
3.32 grains

Standard Deviation:
0.78 grains from mean.


I haven't repeated this with any other coin, but unless I do, I won't have much greater faith in their repeatability. As I write this, I just grabbed the five dimes I had in my pocket and put them on a loading scale. Being the lightest coins they should have the least deviation:

35.1 gr.
34.8 gr.
35.0 gr.
34.9 gr.
34.6 gr.

So a half grain spread. More dimes and it will get bigger.

Nick
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Last edited by Unclenick; September 15, 2011 at 04:32 PM.
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Old September 15, 2011, 04:17 PM   #15
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I have the Lyman

http://www.midwayusa.com/browse/Brow...211***19935***
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Old September 15, 2011, 05:09 PM   #16
Habaz72
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I'd imagine that coins in current production for use as currency take quite a beating... (jingling around in pockets or purses, flinging them at people, fallen on the parking lot and being driven over).. and could have quite the variation to them as noted by UncleNick.

But if you weigh one coin and record it's weight, then keep that coin as your check weight i would think it would suit your purposes just fine.
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Old September 15, 2011, 06:18 PM   #17
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Everyone has at least one buddy who reloads I think. I do. Once in awhile I'll ask him to bring his scale over and we do some comparing which proves both scales. It is at this time that you can make a check weight, or assign something that has been weighed on both scales and weighed the same, to be a check weight. The easiest thing to use is a Match grade bullet. I like to check my scale at max weight and at light weight. I lucked out and found a chunk of brass one day that weighs exactly 505 grains.
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Old September 15, 2011, 06:21 PM   #18
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I think if you picked out a few new coins they would be pretty consistent.
The Amazon check weights are in grams, so would have to be converted to grains.

Not sure what you gain by having that precise of information. If I know the Lee Pro Auto Disk, hole #46 has always thrown 5.0gn of HP38 that is probably what I am going to use, even if my scale is telling me it is 4.99 or 5.1.
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Old September 15, 2011, 06:46 PM   #19
Mike Irwin
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Nick,

Were the coins you weighed from the same year and the same mint?
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Old September 15, 2011, 06:49 PM   #20
wncchester
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"The digital comes with 2 check weights, one 20grams and another 30grams."

I hope you mean 20 and 30 grains.

Your concern over a .2 grain 'error' may be misplaced, it isn't likely to be consistant over the range. The greatest error in any beam scale is - usually - at the max end of the range. And the percentage of error should be consistant, so it won't be off very much at 5 grains.

Second, IF you believe any presumed precise book charge, such as 5.2 gr., is safe simply because it's in a book you are mistaken. IF that were true, there would be no cautions for us to "start low and slowly work up to max unless you see signs of over pressure sooner." A load properly developed and chosen as a "max" charge when using your own scale can be duplicated tomorrow or in 2020 on that scale; repeatability is the kind only of precise 'accuracy' we reloaders really need for powder!
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Old September 15, 2011, 07:03 PM   #21
Scorch
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Quote:
I used the check weight from the 750 to determine that I need to raise the support leg on the 505 beam scale.
Yes, that is how you zero the scale. I usually recommend that owners read the instruction manual to familiarize themselves with proper scale operation.

Check weights are nice, but once you weigh a bullet, coin, etc, you will know what it weighs and can use it accordingly.
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Old September 15, 2011, 07:41 PM   #22
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I don't reload (YET- I'm hoping to get set up after the first of the year) but when I worked at a auto parts store we sold Carburator Float Scales.
They are very accurate and simple to use. IIRC, they were about $15.00 and marked for grams and ounces. You buy (or borrow) a set to double check a "home made" test weight. (NOTE: These are very popular with drug dealers and those who double check their dealers. Might want to mention what you want them for!)
We also mixed paint on a digital scale that would read to .001 gram - I checked the weight of lots of pistons for 'balanced' drag racing engines.
A friendly clerk may let you check your scale against a similar scale.
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Old September 16, 2011, 11:04 AM   #23
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I used my test weights (the ones from Amazon) on my Dillon beam scale last night prior to reloading some ammo.

It's a simple calculation to convert grams to grains.

My scale was close to dead on for all the weights I put on it.
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Old September 16, 2011, 11:21 AM   #24
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Mike Irwin,

No. Definitely not the same. It was a totally random selection on purpose, as the suggestion had been made that all were the same. It'd be interesting to do a sort and see how much closer they are when they're identical.

Nick
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Old September 16, 2011, 03:32 PM   #25
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I know the coins I have definitely weigh less after some merchant pries them from my hands.
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