powder measure suddenly not so accurate...

[rev1911]

I probably have close to 10k rounds through my 550b now (mostly 9mm and .45ACP), and I have always been very pleased with the consistency of the powder measure. When working up new loads, I weigh every drop, and when cranking out mass ammo, I weigh a couple drops out of every 100. Regardless of what powder I use, or how empty or full the hopper is, I rarely see more than .03 difference in either direction. I use a Gempro250, which I know isn't the most precise thing, but I have figured out its quirks, and I trust it.

Yesterday I loaded some Ramshot Comp for the first time, weighing every drop for some ladder loads, and I was seeing much bigger swings. I would dial it in for say 4.2gr, and get a couple 10-drop averages within 41.9-42.1. I'd start loading, get three or four drops at 4.2, and then suddenly I get a 4.14. Then a 4.26. Then a 4.3. And so on. For the life of me I could find no pattern or cause. I just assumed it must be the powder.

So tonight I went back to trusty old N320, and it's doing the same damn thing, randomly swinging as much as .1 in either direction.

I went ahead and pulled the whole powder assembly apart, since I've never really cleaned it. There was a little powder (interestingly it appears to be the Ramshot powder) between the powder bar and the spacer, but other than that everything looks fine. I wiped it all out with alcohol, and gave it a soapy water bath, and now letting it air dry.

Any thoughts? I've read about all the polishing some people do. But it just seems crazy when it worked so well for so long with no polishing at all.

[TDA]

Sounds like a scale problem.

Mine gets stupid when the batteries get a bit low.

Edited December 7, 2015 by TDA

[cnote]

I've gone to a basic beam scale, takes a millisecond more time

[9x45]

Dillon powder hoppers are all around +/- .1 grains, you have a scale problem.

[Hi-Power Jack]

Have you noticed any change in velocity or accuracy?

My guess is that most scales are NOT precise enough

to measure a 0.15 grain difference.

[ChuckS]

I use the Dillon electronic scale but I also have an old 5-0-5 for sanity checking. In addition to the calibration weight that comes with the scale, I keep objects (buttons, washers, etc) that weigh in the vicinity of the charges that I am throwing as check weights. I will calibrate the scale after it warms up and then use the objects as check weights before weighing any charges. I have seen some zero drift but accuracy (or maybe more correctly repeatability) is +/- one count.

Just find some small stuff and test your scale with that which will take the powder drop out of the equation. check for drift and repeatability. The only time I have seen any significant change in dropped charges is when somebody dropped a bullet in the powder column...

[leewongfei]

I used to have that problem. It happeend with lighter powders like W231. As the hopper emptied, the charge would go higher and higher. The more weight on the powder, the smaller the charge (AT least in my case). Either way, i fixed it by installing a baffle in my powder hopper.

[rev1911]

I'm not so sure it's the scale... I use the AC adapter, so definitely not batteries. I have a 20 gram and a 1 gram check weight, and both weighed spot on. Also occasionally when I would get a drop that was more than .1 over/under, I would pull the case and set it aside, weigh a few more drops, and then go back to the one set aside, and it would still weigh the same.

But I guess I should get a second scale to be sure. I'm going to try and reassemble everything tonight and give it another go.

This is the first time I've ever noticed this, so I can't say if it is affecting velocity. I did finish a ladder load of 20 rounds each at 4.2/4.3/4.4/4.5 in the ramshot comp, but I manually pulled any drops (several) that were more than .6 off, so I won't expect to see much in the chrono results.

Thanks for the replies everyone. To be continued...

Edited December 7, 2015 by rev1911

[Hi-Power Jack]

Why not try chrono on the lowest vs the highest drop rates you have =
see if it makes any significant difference in velocity.

Stick a target downrange at the same time and see if the lowest drops
hit a different spot than the highest drops.

I bet you can't tell the difference.

[rustybayonet]

To keep my powder drops close, I found keeping the the tube half to full seems to work for me. When it falls below half is when I see more problems.

[RiggerJJ]

Precision powder barrel from uniquetek.com

[9x45]

You want to run a digital scale off the batteries, not the AC. Also 1 gram = 15.4 grains, you want a check weight of around 4 or 5 grains. A check weight measured on your own scale is not truly a check weight, but rather a reference value for your scale. It should not change over time. Then some powders measure like corn sugar, and some more like oatmeal. Point is whatever powder you are using will have a kinda of standard spread, no point in worrying about it. For an oatmeal powder that throws +/- .2 grains, a ladder test at .1 grain increments doesn't tell you anything.

Jack, Yes, even $20 digital scales can resolve +/= .15 grains, entry level lab scales ($300) can go past .0015 grains and high end (~$25,000) will get you down to .00000015 grains, but you would need a scanning electron microscope to even see a fraction of a single powder flake.

However, for action pistol, where most shots are 3-15 yards, even to 40 yards, +/- .3 grains is not going to make any measurable difference, especially because the shooters small movement far outweighs the variance in powder drop.

Edited December 10, 2015 by 9x45

[Hi-Power Jack]

for action pistol, where most shots are 3-15 yards, +/- .3 grains is not going to make any measurable difference

+1. Shoot 15 of the light weight powder charges, and then 15 of the heaviest powder charges ...

I bet there is no significant difference in POI or velocity.

[phecksel]

You want to run a digital scale off the batteries, not the AC. A

Why?

[Tom S.]

You want to run a digital scale off the batteries, not the AC. A

Why?

Perhaps he's concerned about AC voltage fluctuation. Although the standard for the US is 120V, it will vary, sometimes considerably. In any event, it shouldn't be an issue. Either in the power converter or the scale, there should be a voltage regulator to keep the DC voltage constant. My Dillon is plugged in all the time.

[tires2burn]

Cleaning the powder drop will probably solve your problem.

[Canine582]

voltage levels fluctuate, florescent lights, as you know stated above can cause inconsistence readings. I turn my Dillon scale on for at least a hour before I use it and turn my florescent shop light off while setting up my charge weight. Dillon adds a weight with their scale for calibration.

The only issue I have ever encountered was using 700-X for 9MM's. My readings were all over the place. +/- .04. I bought a aquarium pump off EBay for a few bucks and taped it to the hopper. That got me down to +/- .01. On my second Dillon scale and love it. I run mine off the plug instead of batteries.

[Just4FunLP]

My powder measure went wacky on me once and it was the fact that the spring in the bottom of the fail safe rod (I think that's what it's called) was not being compressed. I turned the plastic wing nut a couple of turns and the problem was gone.

I've also noticed that the charge weight seemed to drift up as I go through the reload session. I think this was due to st he powder settling. I found that tapping the hopper after romping in the powder makes it run consistently from beginning to end.

[mlmiller1]

Ok, this is going to sound stupid so please forgive me but I've found on every dillon I've owned or been around that if the fail safe rod is put back on the powder drop on the right hand side(which always looks natural to me & my dyslexia) of the drop instead of coming in from the left side(looks wrong but matches the assembly pictures), you will get inconsistent drops.

MLM

[Mark C]

I would pull it apart and check for powder residue.

[texasref]

I'm a member of the "take it apart and clean it" crowd.

Also a member of the "half full hopper" (for absolutely no reason).

I do know different powders will measure differently. Not much to be done there, unless you want to weigh every charge and break out the trickler.

I loaded some rounds for a friend using WST & 700X. Drove me mad when compared to 231 or TG. Just too fluffy.

There had to be some variance in charges (no I did not weigh passed the original settings). But all the rounds shot fine.

(+1 Hi-Power Jack)

[427Cobra]

Simple fact, Gempro scales are Chicom junk with a good warranty from a company who stinks at CS, get a beam scale, use it.

[truborshooter]

Winter brings static electricity.

While you clean out the powder measure and hopper be sure to

anti-static it with a laundry pad like Bounce.

Also do the powder measure pan and powder drop funnel

[Dirtchevy841]

Maybe scale prob. Wipe the inside of tube with a old dryer sheet and all moving parts with alcohol wipe. They have a baffle out there for the powder measure that works on keeping even drops. Haven't tried myself but thinking about getting a coupe. Not that much.

[rev1911]

So I thought I'd give an update on this. Before reassembling the powder measure, I gave it a very cursory polishing job with a dremel. Then another soap bath, and put it back together. And I could tell immediately, the whole mechanism was running smoother when I hand cycled it. I tried some N320, and indeed it was weighing with the same consistency I was used to. I waited to try the Ramshot again before making any judgments, because that is what first made me recognize the issues. Well I tried some Ramshot over the weekend, and it metered much better. After settling on a target weight using 10 drop averages, I weighed 20 individual loads, and only two of them were .1 off the target, all the rest were within .06, and the majority were within .04.

I did chrono the last batch of Ramshot where I first noticed the inconsistent drops. It was all once-fired same headstamp brass, and I saw ES of 50-80fps, which is far higher than I usually see. I have new batch here ready to go, so it will be interesting to see how it chronos. The last batch was 9mm, and this new one is 45ACP mixed headstamp, but I'm still very curious.

I know the gempro (and digital in general) have a bad rap. I'm not here to convince anyone otherwise, and I'm under no illusion that my drops are really as accurate to the hundredth is it says they are. But I have been using this one for a while now, I have check weights, and I am constantly trying my own little checks, like taring an empty brass, dropping powder in it, weighing it, then setting it aside. Several drops later, I'll tare a powder pan, dump the brass drop in it, and it always weighs the same or within .02. Things like that make me trust its consistency. That, and I have chrono'd more than a few batches with ES in the teens and single digit SD. I do still plan to buy a backup scale.

So, in this case, I think my press either had enough flakes jammed in the powder bar area to muck it up, or it was just overdue for a general cleaning and polishing, because it seems to have made a noticeable difference.

Thanks for everyone's input, I love this forum.