Please clarify precision powder dispensing.

[big5ifty]

I'll get to the actual question shortly, the background first.

I've been doing some tests [ I have the time ] with various beam scales, and so far, even the oldest one I have, a Pacific, registers measurable deflection of one granule of extruded rifle powder. This oldest one also passes the repeatability test, repeatedly removing and replacing the pan and observing zero.

To be clear, I use a webcam positioned in front of the beam pointer, viewed on a 20-something inch LCD panel. Big magnification, no parallax, easy to observe the slightest deflection.

The cheapest one I have, a Lee, gives the biggest observable deflection by one granule of extruded rifle powder.

I've determined to my satisfaction, using any one of the scales I've tested so far, that I can dispense a powder charge consistently to within one granule.

It is possible to use reference weights to the required charge weight, and zero the beam scale, so you are certain the powder weight is right.

It's generally accepted that en electronic setup is more desirable as it is superior to a beam scale setup, in that it is more accurate to a higher number of decimal places, and is associated with "precision powder dispensing".

So the question :

How does a $1000 + electronic setup, that can detect 1/100th of a grain, dispense a powder charge more accurately and more consistently to less than the weight of one granule of powder , if it only dispenses whole granules ?

 

[762plinker]

quite simply you can view a change, the maker DOES NOT VERIFY to that level.
top end scales are verified to their advertised specs.
do what ever pleases you, but i doubt you will see it used at a benchrest match

 

[big5ifty]

quite simply you can view a change, the maker DOES NOT VERIFY to that level.

If you zero the pan with powder in it, remove the pan, replace the pan, and it's still zero, repeatedly, that is verification in itself.

It's a verified verification, as opposed to a manufacturer statement of verification.

... i doubt you will see it used at a benchrest match

Where it's used has nothing to do with the concept or the observed results.

 

[762plinker]

If you zero the pan with powder in it, remove the pan, replace the pan, and it's still zero, repeatedly, that is verification in itself.

It's a verified verification, as opposed to a manufacturer statement of verification.


Where it's used has nothing to do with the concept or the observed results.

to be clear this is a SHOOTING SITE, not a scale site. we RELOAD to shoot, accuraely, not to claim i have the best scale.

 

[Doug Beach]

The electronic scales, used with the currently available automatic tricklers, will produce accurately weighed charges much faster than is possible with a beam scale. As far as precision, a good beam scale, as it sounds like you have, is as good as you’ll ever need.
I’m not sure why the other guy is feeling hostile.

 

[big5ifty]

to be clear this is a SHOOTING SITE, not a scale site. we RELOAD to shoot, accuraely, not to claim i have the best scale.

You're becoming argumentative without referring to or addressing the question asked in the OP.

How is 0.01 grain resolution better, if one granule of powder weighs more than that ?

 

[big5ifty]

The electronic scales, used with the currently available automatic tricklers, will produce accurately weighed charges much faster than is possible with a beam scale.

Agreed.

 

[SeabeeKen]

I zero my beam scale using a check weight as close to the powder charge as possible before setting the scale to the powder charge I want. I have a redding #2 and an RCBS M1000 and find both are plenty accurate. I get .5" accuracy or better and single digit ES in most rifles I have. I see no difference in accuracy on target between my beans and my electronic scales. I know from personal experience that people can over thinks things. I find myself going back to basics. YMMV

 

[Straightshooter1]

I'll get to the actual question shortly, the background first.

I've been doing some tests [ I have the time ] with various beam scales, and so far, even the oldest one I have, a Pacific, registers measurable deflection of one granule of extruded rifle powder. This oldest one also passes the repeatability test, repeatedly removing and replacing the pan and observing zero.

To be clear, I use a webcam positioned in front of the beam pointer, viewed on a 20-something inch LCD panel. Big magnification, no parallax, easy to observe the slightest deflection.

The cheapest one I have, a Lee, gives the biggest observable deflection by one granule of extruded rifle powder.

I've determined to my satisfaction, using any one of the scales I've tested so far, that I can dispense a powder charge consistently to within one granule.

It is possible to use reference weights to the required charge weight, and zero the beam scale, so you are certain the powder weight is right.

It's generally accepted that en electronic setup is more desirable as it is superior to a beam scale setup, in that it is more accurate to a higher number of decimal places, and is associated with "precision powder dispensing".

So the question :

How does a $1000 + electronic setup, that can detect 1/100th of a grain, dispense a powder charge more accurately and more consistently to less than the weight of one granule of powder , if it only dispenses whole granules ?

Likewise, I've used a webcam positioned in from f my beam pointer and viewed on a large LCD screen. And while, on my RCBS balance beam scale, I could easily detect a deflection of one small granule of powder, that position of the pointer was not of a consistent weight due to differences in the friction produced by differences in the friction at the bearing pivot point. I found the variation in that friction was mostly due to any yaw I would induce on the arm as I set my pan of powder onto the scale. So I learned to be sure an settle the pan onto the scale from the same position to mitigate any yaw pressure I put on the arm and at the same height so the oscillation cycle was the same too. When I was consistent on how I put the pan on the scale, I'd get pretty consistent measurements. But still, not as consistent as is get with my FS-120i.

Of course, if one wants a really consistent balance beam scale, one can always go with a Prometheus.

 

[divingin]

I've had this argument (or heated discussion at least) with my shooting buddies. My side of the argument is that accuracy when weighing is a lot less important than consistency (one of my buddies wants to spend a couple/three thousand dollars to get a scale that will register a thousandth of a grain, because the thinks it will help his groups.)

I don't really care if a 30 grain charge is actually 30.28 gn, as long as it measures that every time. You work up a load not just for your rifle, but for your reloading equipment as well.

 

[big5ifty]

I found the variation in that friction was mostly due to any yaw I would induce on the arm as I set my pan of powder onto the scale.

When I was testing the repeatability to zero on the old Pacific, I found it very sensitive to not being level across the beam pivots. This is probably due to the one pivot being concave. Once I levelled it across the pivots, the repeatability improved.

I also tried a 10-10 and a Lee, they don't seem as sensitive to being dead level across the pivots, I just make sure they are anyway.

 

[M-61]

to be clear this is a SHOOTING SITE, not a scale site. we RELOAD to shoot, accuraely, not to claim i have the best scale.

Wow. Great clarification. I think the last time this OP was on the site the site self appointed unofficial history expert became the site unofficial self appointed puncuation expert. Now we have a ‘topic’ expert.
I’ll write or question whatever I feel like, whenever I feel like it.
And to the OP I’ll say in my opinion anything into the 3rd decimal is probably unnecessary.
My Chargemaster goes to a tenth. I shoot pretty good
I won’t use a period because I don’t feel like it

(100 yard BR)

 

[M-61]

I don't really care if a 30 grain charge is actually 30.28 gn, as long as it measures that every time.

Yup. That's all I care about.

 

[JFrank]

Just to add to the discussion, a scale that’s capable of higher resolution to .01 grain should equal less chance of error at .02 grains.
I would not compete using scale that was off by .28 grains at any distance.
Jim

 

[RegionRat]

How does a $1000 + electronic setup, that can detect 1/100th of a grain, dispense a powder charge more accurately and more consistently to less than the weight of one granule of powder , if it only dispenses whole granules ?

To put it simply, it doesn't.

However, your question is flawed since nobody we are aware of has made the claim that they can dispense a powder charge to less than a granule (kernel) of powder.

On the contrary, the claim is that they dispense to within one to two kernels and the scales (Fx120i) can sense within one.

A kernel of smokeless gunpowder isn't a fixed mass and is very dependent on the specifics of the powder.

A kernel of a ball powder is very small compared to a kernel of H1000 for example.

The Fx120i only claims a milligram capability. A milligram is = 0.015432 grain and since a single kernel of typical extruded powder is roughly 0.01 to 0.025 grains, they can detect a single kernel.

 

[big5ifty]

I think someone with a better mathematical brain can explain this in light of the variation of the average kernel weight.

The measurable difference in charge weight is not one whole granule, it's a a function of the sum difference between a granule, and the average granule weight.

In light of that, it makes a better argument to have a scale that can sense to the difference of a granule and the average granule weight. The same would apply to ball power, the difference is probably a lot smaller.

 

[Mark611]

First off no 2 single grains of powder are going to weigh the same, there might be an average most of the granules fall into, but they are noticeable differences, my A&D HR100AZ will weigh to the 4th decimal, and will show anything powder wise that drops into the pan, individual grains? don't know never tried it, but I can say this if I'm a tic over my weight I can pick thru my pan and look for a granule that looks like it's close to what I need to remove to get my charge weight close to where I want it, I can usually keep my charge weights with in 4hundredths of a grain, I also back up my A&D with 2 beam scales that I have tuned to match my A&D, I throw my charges and trickle up, I do not use a electronic Trickler, it may be a tic faster but I'll stick with what I'm doing, IMO there is no perfect solution, close but no cigar, JMO

 

[jackieschmidt]

In the Short Range game, what most use, (especially in Group Shooting Competition), is predicated on it being user friendly at the range, in between relays, where you have about 25 minutes to get ready for the next relay.

I have a nice Denver Electronics unit that is great in my shop. Out doors, it is just about useless.

The ChargeMaster Lite I use has a great wind guard, and seems to be totally adequate for the requirements of 100/200/300 yard Group and Score matches.

 

[Ralph Littlefield]

How does a $1000 + electronic setup, that can detect 1/100th of a grain, dispense a powder charge more accurately and more consistently to less than the weight of one granule of powder , if it only dispenses whole granules ?

LOL good question.
Perhaps those that have very sensitive scales cut the last granule to get their desired weight.

Edit to add:
When I bought my scale, an Ohaus 1010, fifty some years ago, what sold me on it was a demonstration the shop own gave. He weighed a scrap of paper, then marked on the paper with a pencil. The scale registered the difference. I still think that is quite impressive.

 

[Ned Ludd]

I'll get to the actual question shortly, the background first.

I've been doing some tests [ I have the time ] with various beam scales, and so far, even the oldest one I have, a Pacific, registers measurable deflection of one granule of extruded rifle powder. This oldest one also passes the repeatability test, repeatedly removing and replacing the pan and observing zero.

To be clear, I use a webcam positioned in front of the beam pointer, viewed on a 20-something inch LCD panel. Big magnification, no parallax, easy to observe the slightest deflection.

The cheapest one I have, a Lee, gives the biggest observable deflection by one granule of extruded rifle powder.

I've determined to my satisfaction, using any one of the scales I've tested so far, that I can dispense a powder charge consistently to within one granule.

It is possible to use reference weights to the required charge weight, and zero the beam scale, so you are certain the powder weight is right.

It's generally accepted that en electronic setup is more desirable as it is superior to a beam scale setup, in that it is more accurate to a higher number of decimal places, and is associated with "precision powder dispensing".

So the question :

How does a $1000 + electronic setup, that can detect 1/100th of a grain, dispense a powder charge more accurately and more consistently to less than the weight of one granule of powder , if it only dispenses whole granules ?

There is generally a range of kernel weights, or distribution, around the average weight. How tight the range is will depend on the powder and the Lot#, among other things. When using a quality analytical balance, if one pays careful attention to the actual weights achieved around the target weight when weighing the first few charges, it is not uncommon to to find that many of the individual charge weights tend to cluster around a value close to the target weight, if not exactly on it; i.e. within the weight of a single kernel of powder. By identifying exactly where the charge weights want to cluster within a single kernel of the intended charge weight, it is usually possible to let the statistics work in your favor and achieve a charge weight range of less than the weight of a single kernel. With care, I can usually maintain a charge weight range of about +/- one third kernel, or slightly less than the overall weight of a single kernel.

The important thing to remember about doing this is that we're talking about such a fine charge weight increment/range that in theory it would cause less than 1 fps velocity variance. Is that level of precision in powder weighing really necessary? No. One could certainly get away with markedly greater charge variance before it actually became an issue in terms of precision, dependent on the desired precision level, of course. However, the other way of looking at it is that once the charge weight variance is reduced below a certain level, i.e. it is no longer even close to being a limiting source of velocity error, it effectively ceases to be a "variable" at all. The cost of effectively removing charge weight variance as a source of velocity variance is generally going to be an expensive analytical balance and perhaps more time/effort during the weighing process, so one must decide whether doing so it really worth the $$$, time, and effort for their desired level of precision.