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Discussion Starter · #1 ·
I need something explained to me with regards to the required accuracy of powder scales.

I’m going to be loading a lot of handgun ammunition on a progressive press. I want to get a set of scales that will allow me to develop and check the powder load I’m using to fine tolerances. The problem is that none of the “usual” digital scales I see for reloading are capable of weighing smaller than a tenth of a grain. In other words, they are rated as being “plus or minus” one tenth of a grain.

Now if I understand this correctly most loads are developed to a tenth of a grain. For example I might want a powder charge of 5.2 grains or 5.7 grains. With a scale that can only weigh to “plus or minus” one grain, how is this going to work? The powder charge being weighed could actually be 5.5 grains but the scale might show that as 5.4 grains or 5.6 grains. So how on earth are you going to know if you actually have 5.5 grains? Or for that matter, how are you going to tell if your powder bar is throwing the charge you want?

Would you not need a scale capable of weighing to 100th of a grain? In other words being accurate to “plus or minus” .01? That way a charge would show as 5.51 or 5.59 and at least you would know you were “about” where you wanted to be.

Or am I missing something here?

If it’s not important, then why do we worry about measuring powder charges to the tenth of a grain? For example, instead of thinking in terms of a 5.5 grain charge why not just call it a 5 grain charge or a 6 grain charge?

As far as I can see none of the digital scales being offered by the usual crowd (Dillon, RCBS, Lyman, etc) are accurate to anything beyond “plus or minus” one tenth of a grain. The only affordable scale I’ve found that can go beyond that is the Acculab VIC-123 which is capable of “plus or minus” 1/100 of a grain. There are others obviously, but that one seems to be a decent unit and is semi-affordable at around $250 US

I’d appreciate some input from the more experienced loaders here. Thanks.
 

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The Troll Whisperer (Moderator)
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Even beam balance scales are difficult to measure less than +_ .1 unless you put some big bucks down.

In your normal shooting, plus or minus a tenth of a grain will not show up on the target. Trying to split fine hairs when weighing propellents will be a sure way to drive you nuts. There are so many other variables in the process of reloading a cartridge that the minor variance in powder weight is negligible.

Is over 50 years reloading enough experience to qualify here?

I commend you for striving for perfection, though!
 

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Discussion Starter · #3 ·
Thanks KDUB. Yup, you definately qualify as an expert with that much time into the hobby. So basically if I just go the Dillon (for example) digital scale and got things to where it weighed the same to a tenth "most" of the time I'd be close enough?

Of course that brings up another question, which of the more commonly available digital scales (Dillon, RCBS, Lee, Lyman, etc) is the best? Or are they all essentially the same but different colors and with different labels.

I don't want or need a scale that dispenses powder. Just one that measures as accurately as possible.
 

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Piney Woods Moderator
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Another way to look at it is if you are using a progressive loader, the powder measure that will be dropping your charge will only be accurate to + or - a tenth of a grain or so. Even if you find a scale that measures to a thousanths of a grain, your mechanical powder dispenser will never meet that standard so why worry. If you are going to weigh each load, why use a progressive loader.
 

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And, even if you could drop the powder more accurately than the scale measures, you wouldn't want a load so sensitive that a tenth of a grain mattered. Such a load would go in an out of accuracy with relatively moderate changes in temperature, since such changes have impact that exceeds the effect of one tenth of a grain pretty easily.
 

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"In your normal shooting, plus or minus a tenth of a grain will not show up on the target."

Roger that. Nor even +/- .3 gr. in most reloads, ESPECIALLY so for most handgun ammo. If digital (or beam) scales HAD to be "more accuarate" than they are I suppose most of us would already have our hands blown off. And consistancly-repeatablity is far more important than pure accuracy anyway.

I don't and don't know of anyone else who weighs individual charges of pistol stuff, dropped is good enough. Only a noob considers small charge variations to be critical, you'll soon outgrow it. ;)

Digital scales are no more accurate and are usually less sensitive than a beam scale. If a digital is "faster" depends more on how well we use a beam than any blinding speed of electonic scales.
 

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I have known 2 very experienced reloaders/match shooters who would not be satisfied with a match load's accuracy, unless they could go up or down one tenth of a grain in charge weight, without a substantial impact on their group size. One old gentleman, in particular, was highly enamored of IMR-4198, as he claimed it was particularly capable of creating similar pressure/velocity, even with as much as .2/gr changes in the charge. His groups certainly suggested he knew whereof he spoke.
 

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The Hog Whisperer (Administrator)
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I'll go with the above. Plus or minus a tenth is certainly good enough for me. In addition to the powder charge variance, you can have a variation in the capacity of the individual case that will amount to more than a tenth of a grain of powder.

If I was concerned that another tenth would put me over the edge..... I would re-think what I was doing, anyway.
 

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If I was concerned that another tenth would put me over the edge..... I would re-think what I was doing, anyway.

That's a good way to be thinking about this topic. Is best to just stay away from that "edge".

Real good loads can be found "far from that edge".
Putting a good bullet in "the right spot" is not about being on that edge.

IMO

Cheezywan
 

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Discussion Starter · #10 ·
Thanks Gents. I had no intention of loading to the "edge" where a bit more could be a problem, but was just not sure how accurate I had to be. Now I know. So as long as I'm within that tenth that most scales can measure - more or less - that's good enough.

Especially the way I shoot! :)
 

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If I really want to get picky I'll use my jewelers scale, that thing will measure a postage stamp, If anyone decides on purchasing one make sure that it has a weight in grains function, unless you really like doing math, their around 30 bucks a throw for a fairly good one.......stegmaier
 

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"One old gentleman, in particular, was highly enamored of IMR-4198, as he claimed it was particularly capable of creating similar pressure/velocity, even with as much as .2/gr changes in the charge. His groups certainly suggested he knew whereof he spoke."

Yes. But, please note that I said "most reloads", that sorta suggests, "not all." ?? Your friend shoots a very small cartridge (IMR-4198 size) so the percentage of change with small charge differences will certainly be greater than with most cartridges.

That said, a bit of experimenting will show that MOST rifles, especially factory sporters, will shoot their best with charges that can vary over a moderately wide range with no difference. It can be as much as .5 gr or even more with larger cases; anything inside that range will make no perceptible accuracy change at all. Load in the middle of that window and all will be well, we'll have a much less twitchy load and far fewer "fliers." But, load at a ragged edge of that window, high or low, and we WILL see some quirky accuracy! Just depends on how well we know what we're doing.
 

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We tend to measure that which we can measure, and if we can measure it more accurately we tend to want to do that, too. This is regardless of how important or how much the quantity impacts anything. It's just natural, I think, and often, it's just fun.

But, for $65-75 you can get an electronic scale that measures to +/- 0.002g with a 20g capacity, which is about +/- 0.03 grain. One is the Mack 20, available at about 100 different places online. Comes with a calibration mass, bubble level built-in, large clear top door, and reads out from two sides. Here's just one source: http://www.oldwillknottscales.com/jennings-jscale-mack-20.aspx

The unit reads out in selectable units including, g, gr, kg, lb, ct, dwt, ozt, oz and mg. It will show 'gn' for grains, not 'gr'. One thing such a scale does is make it easier to see the limitations of a volume-based powder measure; but, as everyone has pointed out--those limitations are well below the threshold of impacting metal-on-target.

It includes two small plastic pans, neither of which is very immune to static charge. But, replacing the plastic pan with an aluminum foil one can address the static issue if there is one. I like to throw 10 charges into the pan to see what the average throw weight is, and I do that a couple of times throughout the load session. Lately, I don't worry about it--I'm loading .45 ACP after all. My experience is very limited, but even down at the 3.4gr to 4.0gr charges of Clays in 45, it looks to me like the Threshold of Concern is no less than .2gr or so.

What I'd like to see is loading manual charges also given in milligrams, and the top of the page labeled "All charges given with a tolerance of +/- 10mg". Then you'd have something. This would also provide an endless source of bickering, stomping and spitting on the internet--and I can hear the screams now--the sound of millions of souls burning in **** itself.
 

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"One old gentleman, in particular, was highly enamored of IMR-4198, as he claimed it was particularly capable of creating similar pressure/velocity, even with as much as .2/gr changes in the charge. His groups certainly suggested he knew whereof he spoke."

Yes. But, please note that I said "most reloads", that sorta suggests, "not all." ?? Your friend shoots a very small cartridge (IMR-4198 size) so the percentage of change with small charge differences will certainly be greater than with most cartridges.

That said, a bit of experimenting will show that MOST rifles, especially factory sporters, will shoot their best with charges that can vary over a moderately wide range with no difference. It can be as much as .5 gr or even more with larger cases; anything inside that range will make no perceptible accuracy change at all. Load in the middle of that window and all will be well, we'll have a much less twitchy load and far fewer "fliers." But, load at a ragged edge of that window, high or low, and we WILL see some quirky accuracy! Just depends on how well we know what we're doing.
I think you felt I was refuting something you said, and I assure you I was not. I actually was writing a response to the thread before yours ever posted, so we were both basically saying the same thing.

Where you have confused me, though, is your reference to IMR-4198 being a "very small cartridge" powder. I'm not sure how you arrived at that conclusion, but while it is one of the faster rifle powders, it is applicable in a wide array of cartridges, large and small, as any load book will confirm. The 444 Marlin and 45-70, just to name a couple. It even provides better than 80% load density in '06-based cases, though I'm not suggesting it would provide ideal performance in those.
 

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"I think you felt I was refuting something you said, and I assure you I was not. I actually was writing a response to the thread before yours ever posted, so we were both basically saying the same thing.

Yes, Broom, I did but I wasn't offended at all, it's opinon and I don't get upset when people disagree. Mostly I wanted to expand on my original comments to better clarify what I meant. :)

Okay, so I dint clearly say what I meant or assumed your old buddy was doing. 4198 is a very good small rifle cartridge powder, Bee, Hornet, triple deuce, and .1 gr could perhaps put someone outside a narrow accuracy window for that. But even tho IMR 4198 also works well with large straight wall cases, I doubt a .1 gr. variation will do a thing to anyone's 444/45-70/450/460, etc. load, do you?
 

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Nope, in those big jugs, I doubt anything less than .5-1.0 grain would be noticeable, unless you were already very close to a maximum load. If I remember correctly, Al (the old gentleman I was referring to) was shooting a 6mm PPC when he made the comments about 4198 being less sensitive to loads being off a little, either way. Keep in mind that he was shooting for groups that were consistently 1/2 MOA, so his definitions and tolerances were a little different than most.
 

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One of the factors that has always been a little surprising to me is how few BR competitors weigh charges at all. In fact many couldn't even tell you what weight they are shooting. Many - most? - of them use click-adjustable measures and can tell you exactly how many clicks of a given powder they drop but not the weight!

My old BR rifle in 6MM International still shoots 3/8" or better but it can't tell any difference with powder charges inside a .3 gr window. (And I DO weight.) All that means the precise accuracy/consisitancy/sensitivity of any scale reading to .1 gr is far better than it need be for reloading work. A Promethus scale is nothing more than an anal and very costly curiosity, it adds nothing to the accuracy of the loaded ammo, internal case variations normally have more effect than .1 gr. of powder!
 

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Ranger,

There is a theory that volume is a better measure at a given range session because bulk density can change with humidity within the period of that session, and therefore volume gives you more consistent energy content. I'd want to see that proved, but it is clear a measure is quicker and easier to use at the range than a scale, and is probably a good bit more consistent when you are outdoors and there is a breeze blowing across the scale pan. A lot of the BR guys want to load just a few particularly good cases over and over, so they have to reload at the match.

Dan Newberry's OCW system is devoted to finding loads that are immune to charge weight over a 0.6 grain span (+/- 0.3 grains), at a minimum. You might enjoy reading through his pages? I now use his round robin rather than Audette ladders and have had only positive feedback from others I've talked into trying it.

Newberry eschews fancy loading tools and gauges, finding he can get most rifles down to half an moa without any of that. Once you do that well, of course you can then start applying the specialty toys to tighten groups down still further, but Newberry gets you to a good starting point.
 

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I know the volume vs. weight argument. Perhaps when loading manuals start giving charge data in CCs I'll try it. But not yet.

I'm also sure the OCW load finding method works good. I find the ladder method to work well for me, as well as allowing me to find the total window of a good shooting charge range. Most reloaders would be shocked to learn how little value there is in getting their precision charges weighted to +/- .1 gr., or even +/- .3 gr. if it's really a good load!
 

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I know the volume vs. weight argument. Perhaps when loading manuals start giving charge data in CCs I'll try it. But not yet.
The Lee 2nd edition book gives the volume info in cc's.

Looking at the OP, I'd like to throw a comment in here. My job is as an instrumentation and calibration technician. I'm going into my 30th year of doing this. Scales, both digital and balance beam are something I do calibrations on (along with temperature, flow, pressure and many other measurements)

On the request for an accurate scale. What he really wants is a scale that reads to a specific resolution.

Here's where people get confused. Reading resolution and accuracy are not the same. A lab scale can have a display that reads 0.001 grams (which equates to .00015 grains). That is the resolution. The minimum accuracy for any digital display is +/- 1 least significant digit (LSD). It is typically greater than that. For example, the lab scales I deal with, costing in the thousands of dollars, are at best +/- 0.01% of the full scale plus 1 or 2 LSD's

What is not included in this number are values called linearity, hysteresis, and repeatability / stability. My cal reports for companies reporting to the FDA and the NRC require adding all these factors together to report the total probable error- which is ALWAYS a larger number than the resolution and accuracy.

So for scales, the resolution is the smallest readable digit and the accuracy will always be a number that is greater than that. So a measurement reading 10.1 grains on a scale with a resolution of 0.1 grains with a TPE, or total accuracy if you wish, of +/- 0.15 grains can actually be anywhere from 9.95 to 10.25 grains.

Now most powder scale manufacturers do not concern them selves with using correct terminology as the reloading public at large is not aware of, nor do they care about, these details. I know them because of my occupation.

So that said, here's how you can apply that knowledge. Warning: this is only for people who like to be anal retentive about their measurements ;)

Make sure the scale is on a LEVEL hard surface

1. Accuracy / linearity
Always use the same scale when measuring loads. If you have 2 scales, check to make sure they give the same reading at 10%, 50% and 90% of their range if you want identical loads. They may have different accuracies or the linearity may be different even though the resolutions are the same. A single point check only proves they read the same at that one point. Use the same weights with both scales. If they don't read the same, use only use one scale.

2. Hysteresis
Always approach the measurement from the same direction. If you added powder to get the initial measurement always reach the weight by adding powder. If you go over, remove enough powder to go well below the required measurement (say 10%) and then add powder back to your desired weight

3. Repeatability / stability
Make sure your room is close to the same temperature when working. The scale itself is a mechanical device and temperature changes will affect the scale to a small degree (usually only see a significant change with temperature changes greater than 20 degrees)

4. Technique
The further you are from dead center, the greater the chance of introducing a small error unless the plate is specifically designed to handle off center loads. Having never calibrated a powder scale, I don't know if this is the case.

From the other posts explaining how small deviations in charge not making a big difference in accuracy (unless you're close to max pressure), this type of care when measuring is overkill. But, if you want to be as accurate as possible, this is how to do it.

Other things to keep in mind- always measure with the scale sitting on a hard surface.

The less the scale is transported and jostled, the longer it will hold it's calibration. If you take it with you, pack it in something to absorb the shock.

If you drop it, check it with a known weight. Weigh a couple of metal objects when you first buy the scale ( a nut, a screw, etc). Store them for checking the scale at a later date and write down the readings. Now you have your own set of "calibration weights". If the reading is off from these initial readings after dropping the scale, see if the maker will calibrate it for you.
 
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