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Discussion Starter #1
Are the calibration weights (ie: Lyman, RCBS, etc) any higher quality that the calibration weights that come with your scale? I recently acquired an MACK 20 and the calibration weight that comes with it doesn't seem to be of high quality. I suppose the weight that ships with the scale is of equal quality of the scale itself, as, what's the point? :confused:
 

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Yes , I have 7sets of scales on different places on my benches & check each set before starting to use em .

Cheap peace of mind !!
 

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I also have the Mack 20, and agree that this 20 gram weight doesn't have the "high class look" of my other check weight set. It does the job though, so I wouldn't worry about it. As a matter of fact, my other check weight set has 2 10 gram weights along with an assortment of 5, 2, and 1 gram weights. The Mack 20 shows that there is a very small difference between common weights, it gets into the 0.002 to 0.004 gram difference. I love the resolution and repeatability of this scale, and see no reason to use anything other than the check weight provided.
 

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MidLife, There are several different classes of calibration weights, depending on how accurate you want/need and how much you want to spend. I have a set of Ohaus calibration weights (M2 Class) that I bought many years ago for about 25 bucks. I thought they were pretty accurate when I used them on my RCBS balance beam scales. When I got my Mack 20, I was very disappointed to learn the calibration weights were not as good as I had thought. The set comes with one 1 gram, two 2 gram, one 5 gram, two 10 gram, one 20 gram, and one 50 gram weights. When I tested both 2 gram weights, one weighs high, the other low. The very same thing with the two 10 gram weights. The 20 gram weight that came with my Mack 20 weighs a tad high and the one in the Ohaus set weighs low. My Pact scale came with two calibration weights, one 20 gram and one 30 gram. So in total, I had three different 20 gram weights, none of which weighed exactly 20 grams, two slightly heavy and one slightly light. I calibrated the Mack 20 three different times with the 20 gram weights .... once with the included weight, once with the Pact weight, and once with the Ohaus weight. The end result was nearly identical when I tested and documented the other weights in the Ohaus kit. I had thought about springing for a Class 4, 20 gram calibration weight (over $40 for a single weight) but gave up on the idea partly because of cost but mostly because I doubt if it will make a significant difference in my Mack 20's calibration. BTW, all the weights in my Ohaus kit, the Pact weight, and the Mack 20 weight were within .05 grains, which is match grade accuracy for powder charges. When using my Pact BBKII (accurate to .1 gr) it read dead on with all the calibration weights.

With any powder scale, you are not as concerned with actual weight as you are with repeatability. Yes, you want accuracy but repeatability is way more important. If you are dropping 5 grains of powder and the actual weight is 4.9 gr .... no big deal but when you weigh multiple loads, you want good repeatability or your powder charges will vary. On my balance beam RCBS scales (supposed to be accurate to .1 grains) I found repeatability was grim (+ or- .2 grains was normal ... .4 gr max spread) until I modified my 510 with the vibrator motor. With the vibrator on, I could get +or- .1 grain repeatability (.2 gr max spread) at the low end. With my Mack 20, I found repeatability was about +or- .02 grains (.04 gr max spread). Although not perfect, a .04 gr max spread is way better than my RCBS 510 with the vibrator or my Pact BBKII (about 5 times more accurate and repeatable).

Bottom line ... you aren't going to get lab quality accuracy with any scale under $1000. The standard for powder charges is +or- .1 grains for normal loads and +or- .05 grains for match grade loads. The Mack 20 is more than capable of match grade accuracy and more importantly, its repeatability is way better than any normal reloading scale ... digital or balance beam. Here's a link to the high $$$ 20 gram calibration weight:
One ASTM Class 4 20 Gram Calibration Weight
 

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Discussion Starter #7
Thanks all.

Iowegan, is the calibration weight included with the Mack20 accurate?
That's the substance of my question. In other words, is their scale more accurate than their included calibration weight?
 

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check weights

I have a set of weights that I have had for over 30 years, unlike most they are not even gram weights but rather are marked to the nearist .1 of a gram. They were individually weighted and the actual weight of each shown. I have no idea were I got them. I trust them.
 

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When I first got my Mack 20, it had been lost in the mail for two weeks. When it finally arrived, it was not in good working condition. The company I got it from sent another one out and it worked. I kept the calibration weight from the first one and it does not weigh the same as the second one. Does it make a difference? I really don't know. I do know that I have loaded thousands of rounds and been able to be consistent. That's good enough for me.
 

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Discussion Starter #10
I kept the calibration weight from the first one and it does not weigh the same as the second one.
I would not be surprised. Just looking at the included weight you can tell it's not to the precision their scale is supposed to resolve. On mine, the handle of the weight unscrews, too! Also, the weight was scotch taped to the outside of the cardboard cushioning and I almost threw it out with the trash! I had to get some glue remover to take off the residue. i suppose the scale is worthy of a real calibration weight. Too bad the scales don't use a consistent calibration weight! Each of my scales uses a different weight. One of them even uses two weights, as the calibration is done in two steps.
The reason I ask all of this is my scale is off by 2/10s of a grain but i don;t know which way!
 

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MidLife, I can't answer your question for a couple of reasons. First, I don't know how far off your 20 gram weight is and second, calibration works a bit different than you might expect.

The algorithm for calibration compares 20 grams with zero grams and takes an average. So automatically, the error rate of the 20 gram weight is cut in half. Here's the math ... let's assume your 20 gram weight was exactly 1 grain too heavy. The algorithm would then average this to .5 grains at the high end. 20 grams = 308.69 grains, + .5 grains or 309.19 grains. This is an error rate of .16%. If you weighed an exact 10 grain powder charge, the adjusted weight would be (.0016X10-10=9.984) 9.984 grains. Because the resolution and accuracy of the scale is .02 grains, the display would read either 9.98 or 10.00. Worst case, you may be off by .02 grains, which is so minute it isn't worth worrying about. Each full grain of error in the calibration weight accounts for about .016 grains of error in a normal powder charge. To put this in a better perspective, when you consider a balance beam scale on it's best day is only accurate to .1 grains, .016 grains is down in the noise level.

You should be able to compute your error rate by weighing your 20 gram weight in grains (after calibration) then subtract 308.69 from the weight displayed. Multiply the result by .016 and you will have the error for a 10 grain powder charge.
 

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Somewhat of a hijack...

Dangit Iowegan, you are gunna get me in trouble! Now I went and bought that Mack 20 scale because you have nothing but good stuff to say about it.. Boy am I gunna hear it when my wife receives the package at the door.. "You ordered MORE stuff?!" (of course because my CMP M1 Garand got here last week)

Do you trickle directly into the scale? how do you do it personally?

Anyways, thanks again for steering me in the right direction for the digital scale.. I think my balance beam will go back in the box for a while until I need to weigh my arrows again..
 

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GMinor, The Mack 20 comes with a funky plastic pan so I use the aluminum pan from my RCBS 510 scale. All you have to do is switch the scale off, set the pan on the scale, then switch it back on. It will automatically zero and is then ready to start weighing. Yes, I trickle directly into the pan and the scale tracks very well. Depending on what trickler you own, you may have to raise it up to get the auger spout high enough. A plastic bullet box works great. I made a super wiz-bang electric trickler out of a RCBS trickler, a geared motor drive from a toy, and a Speer bullet box. It has three switches for three speeds and because the bullet box elevates the auger spout, it works perfect with the Mack 20. Here's a photo:

 

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Iowegan I have to say I have now darn near seen everythiing. A motorized trickler...who would have thought.:D I bet it works slick.

Take Care

Bob
 

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Ale-8(1), You have a point! Does the name Rube Goldberg ring a bell? I know it looks pretty shoddy but I have been using it for about 5 years and it does work exceptionally well.

Several years ago for Halloween, my wife bought this crazy electronic gizmo that is a candy bowl. When a trick-or-treater goes to grab some candy, a light sensitive cell picks up the movement and a hand comes out of the bowl in addition to a scary "Happy Halloween" voice. After a couple of uses, the cheap ass thing broke so I tore it apart to see if there was anything worth putting in my junk box. Turns out, the geared motor for the hand gave me an idea and the above is what developed. I can't take full credit for inventing a motorized trickler ... Frankfort (Midway USA) used to make one but it got discontinued .... probably because there weren't many people as crazy as me that wanted to buy one.
 

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Well, I'll tell you what. Iowegan, you are a man among men.

Aside from that, I ordered that Mack 20 from old will knott scales (something like that) along with the a/c adapter this morning (reference above post). And I already received a UPS tracking number (@ 0948) and all. It is already on it's way to CA! Talk about fast!
 

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ColColt, If you want everything in one unit, this is the cat's ass. The AUTOSCALE is intended for extruded rifle powder but can be adjusted for heavier pistol charges too. It doesn't work very well with charges under 10 grains.

After leveling the unit and filling the powder hopper, you start by setting the scale poise weights (identical to a RCBS 510) to the desired charge weight. When you press the green button, a high speed and low speed auger start dispersing powder in the pan. When the charge weight gets close, the high speed auger stops and the low speed auger continues to trickle until the scale pointer is dead on the mark, then shuts off. You are then ready to pour the powder in a prepared case. For a 50 grain charge, it takes about 10 seconds to precisely measure out a powder charge. I've had this AUTOSCALE for several years and use it when loading rifle ammo on my Rockchucker. It works super and accuracy is +or-.1 grains. The newer digital scale auto powder dispensers work much the same except the scale is digital and you set the desired charge weight with a key pad.

The nice thing about either the balance beam or digital powder dispenser is everything is in one package. You don't pre drop from a powder measure then trickle up like in the Youtube .... just push a button and a few seconds later you have a precision powder charge.

The electric trickler I made works much the same as the one in the Youtube video, but it sure doesn't look as nice. Mine has three speeds ..high will drop about 30 grains per minute, medium drops about 18 grains per minute, and low drops about 6 grains per minute. Once you get the hang of it, you can trickle up a charge on the Mack 20 scale accurate to .02 grains and rarely go over weight.

Here's my old AUTOSCALE:

 
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