went and ordered a hornady auto charge powder dispenser. Been having trouble out of my old RCBS beam scale, and my Lee beam scale bugs the crap outta me. So wish me luck, it should be delivered by the big brown truck today.
www.hornady.com/store/...dispenser/

Make sure you give us a report on it, including photos...

Been considering one myself.......... I'll be interest in your report back !!!
(Looks a lot like the RCBS unit ???)

Yes a report would be great, a shooting buddy bought an RCBS unit a few years ago and watching him use it was tedious to say the least. Maybe because it was one of the first models but when you programed it for your load, the last 1 1/2 to 2 grains would trickle in, SLOWLY. In fact, for a mid range /06 load, it would take almost 90 seconds to measure and dump load. He called RCBS and they shipped him a new one and it did the same thing, but he's in no hurry just as long as its accurate.


Hopefully newer tech speeds it up.

I've got a PACT and am pleased with it. One solution to a long dispense time is to throw most of your charge with a manual powder dispenser then let the automatic one trickle in the remaining amount. I've done it by setting my manual dispenser to throw a charge 2-3 grains low before sticking the pan on the PACT.

How accurate is it and how accurate do you need it to be?
Seriously – we all want our loads to be the exact same weight but even though a scale says the same value on the digital print out or on the center line of the pan balance arm, is it?
A grain is not very much and a 1/10 of a grain is , well less than that... One grain is .0648 grams or 64.8 mg. 1/10 of a grain is 6.48 mg or .0065g.
Most digital scales say they are accurate to 1% (.01) but may have a read out that has a lot more decimal places than it is accurate to.
And furthermore, ( Heresy and Blasphemy) does it matter?
In my testing I have found in a .223 with a 77 grain SMK that with Varget /RE-15 and 8208XBR you get about 10 fps increases with a 0.1 grain charge increase. But with ES and SD there is overlap. Put that on
Paper and run it through point blank and you will find that even at 0.5 grain or 50 FPS difference the POI at 300 yards is a whopping 0.2MOA. I sure cannot hold that tight. I used to be very meticulous about weighing each charge for competition but since I figured this out I set the powder thrower and spot check about every 10 throws. My scores have improved because I shoot more and spend less time at the bench.
That said, any load I shoot over 300 yards gets the royal treatment of brass prep uniforming and weighing for maximum consistency that is designed to give me the lowest ES possible so that any points I lose at 600 yards are from my missing a wind call and not from a change in velocity between shells.
DO NOT READ THE REST OF THIS POST UNLESS YOU ARE A GEEK


In Pharma, to use a balance for assay it has to be repeatable and accurate to .001 or 0.1%. We calculate the repeatability by taking 3xSD/weight used. (Nasa uses 2xSD/weight)

I typically will use a five place balance and get an SD of .000006 or better using a 20mg weight. 3x 0.000006/.020 = .00095. If I use any lower weights the SD will go up and I will fail this test. .020g or 20 mg is the minimum weight I can measure within the precision of my $$$$$ scale...( I just checked six of them and they all have a similar floor of about 20 mg.) We have six place microbalances which will go down to 2mg accurately weighed. Even though they will display 0.01900g or 0.00190g they certainty of a measurement less than the minimum weight is outside the allowable range to be used in a pharma test.

If you are using a scale that is only reading to 2 decimal places, you cannot get repeatability to that level. USP uncertainty calculations would say that his scale is repeatable only with weights over 20 grams to have 0.1% repeatability! (Since it is three orders of magnitude less precision than my balance) that is 308 grains to pharma repeatability requirement.

Here is a test for you to try - Pick check weight that is about 5% of your scales capacity ( ie 10 grams if your scale is a 200 gram scale) Get it good and warmed up, eliminate all vibration, thermal variation, static charges and any drafts blowing through the area - Zero/calibrate the balance if it has that feature, then take 10 replicate measurements of the check weight and see if you get the same reading. If you get the same reading use a smaller weight and repeat.

If you do not get the same reading all 10 times - calculate the SD of the 10 measurements to one more place than your scale reads.

For example If you take 10 readings and 9 of them are 10.00g and one 10.01 your SD is .003g.

Using the calculation above you can determine a minimum weight that will meet your precision requirement. If you need 0.1% (.001) repeatablility at the 2SD Nasa requirements( this is Rocket science not 3SD brain surgery):

2x SD /.001= Minimum weight

2x.003/.001 = 6g (92 grains!) minimum weight that can be accurately weighed with 0.1% accuracy.

If 1% is good enough precision for you that will drop to 9.2 grains for a minimum repeatable measurement.

This should not stop you from wanting to use electronic balances, just make you aware of the limitations and allow you to have reasonable expectations of the results.

One grain is .0648 grams or 64.8 mg. 1/10 of a grain is 6.48 mg or .0065g.
If your balance is not reading grams out to at least 3 decimal places (MILLIGRAMS) you will have a lot of variation in what it shows as a 0.1 grain change. With one decimal places 23.9, 24.0 and 24.1(grains) all read 1.6 grams. Two decimals would read 1.55, 1.56 and 1.56 grams. Finally with three decimals you would see 1.549, 1.555 and 1.562 grams. (My four place balance would show 1.5487,1.5552 and 1.5616g)
If you do the conversion to grains and round to the 0.1 place… a balance could read between 23.1 and 24.7 grains for the same measurement if your balance reads to the 0.1gram
grams grains
1.5552 24.0
1.555 24.0
1.56 24.1
1.6 24.7
1.5 23.1

Crap, Dawgdad, I enjoyed reading that. I didn't know I was such a geek.

CRAP....my head hurts.

Cheers, Vince

I got a sore head too. Im quite happy with my balance beam that gives me 1/10th of a grain measurements. I will throw a charge and then check it in the pan , then load it.

You make a Good point Dawgdad, but do we really need a scale/dispenser that accurate for our hunting loads?

Its getting to the point where weighing powder charges to a hundredth of a grain is like trimming firewood with a finger nail file.

OV1 wrote:

...trimming firewood with a finger nail file.

You say that like its a bad thing mate...don't you do that anyway???

You make a good point though...1/10th of a grain is about as close as the average Joe with the commonly available scales can get anyway. With the different types of powders...log, ball, flake...and the "small" inconsistencies of production, I think it would be difficult to get a consistently spot-on accurate measurement anyway.

Cheers, Vince

About 18 years ago I sent an e-mail to RCBS asking if they would ever produce a scale that could weigh down to .01 of a grain.

About two days later I got my answer. "Ha ha ha ha...Right" Signed "Director of manufacturing"...

Well Donut Slayer? Did it come in?

Bushmaster wrote:

About 18 years ago I sent an e-mail to RCBS asking if they would ever produce a scale that could weigh down to .01 of a grain. About two days later I got my answer. "Ha ha ha ha...Right" Signed "Director of manufacturing"... Well Donut Slayer? Did it come in?

yes it did. So far, it seems very accurate. Have to let it warm up for about 5 minutes then calibrate it, but no biggie on either. Tried it with H4831SC, threw about 100 charges at 62.0 grains, 98 were all on and 2 were .1 grain high. Thats on the fast setting. I didnt time it but it threw a load about 45 seconds. Now when it came to flake pistol powder, Bluedot @10.0 grians, damn it took forever. Like about 2 minutes per charge. It would throw to 9.8 or 9.9 and seem to take a full minute to dispense .2 or .1 grains. I havent had a chance to play with it alot, but I'm sure liking it right now. Set the target weight and it will beep when it's done. NICE.

Oh, and the reason I decided to get it was, every once in a while my RCBS scale would act crazy. I mean, the beam would stay just under the balance point while I trickled powder then all of a sudden it would tipp straight up. WTH?????? I would take it apart (assuming dust) and clean it, wipe it down with a anti static dryer sheet but it would still malfunction. The next day it would be fine. There would be no air currents, no radio interference or any thing that I could figure out. My Lee scale wouldnt be affected, but I really dont care for that scale.

Make sure the two knife edges are clean and burr free.