[DragonFire]

I have a Dillon Square Deal-B press, and over the last couple of days I've been set up to load .40 S&W rounds with 6.5 gr of WSF (Winchester Super Field).

After initial setup I was checking 2 or 3 rounds out of every 100, and each time the powder weight was right on +/- .1 grains. When I had about 1600 rounds loaded over the last 3 days, the weights suddenly changed to 5.8 gr.

I stopped and threw some more sample loads, and all came out right out 5.8 grains +/- .1 I dumped my powder measure cleaned it out a bit, and refilled it and tried again. Weights were back out 6.5. But a few rounds later they were right back at 5.8

Keep in mind that the weights were inconsistent, they stayed within +/- .1 of a grain, but they had dropped about .7 grains.

The one thing that had changed was the humidity. We had a sudden thunderstorm, and the humidity went way up. Could that have caused the powder to clump together more, and change how much powder fit in the powder measure?

I did a search of this forum and found some threads on static build up. Could static have built up? Would that have affected the weight? Have anyone of you had this problem?

Should I just use a dryer static sheet on the powder measure every once in a while? The thing that bothers me is that the powder weights weren't inconsistent, but stayed within +/- .1 of a grain, but the set weight changed from 6.5 to 5.8

And I would think the high-volume presses would always be having problems. I only do 200-300 rounds an hour, a press doing 500-600 an hour should be building up status at more than twice the rate.

Luckily I was loading .40 cases where I could see the powder in each case. If I was doing .38 or .357 I wouldn't have spotted anything.

[Ol` Joe]

How low did the powder level get in your hopper? The wgt of the powder changing will sometimes cause the measures to toss less as the level drops.

[DragonFire]

I was keeping an eye on that, and the powder was pretty well full.

[Dr. Dickie]

Do you always have it full?
Reason being, if the powder is prone to packing, a full hopper may pack the powder below it, and cause so light loads. If if it still doing it, try only filling the hopper up half way and see if it persists.

[JackOfAllTradesMasterAtNone]

I have Dillon powder measure too and have found them to be the most accurate and consistent on the market. The charge bar returns by aid of a spring. Could it be that the charge bar has found a new 'home'? A bur or clump of powder in the slide/chamger area?

Might be a good question for Winchester/Olin to answer regarding static component density at varying humidity conditions.

-Steve

[Grump]

IME, some powders pick up humidity more than others.

AA-2230-C, for example, picked up .7 grains going from 20% to 80%+ humidity (3 days' exposure in the pan on the scale), but that was for a 5-charge sample of something upwards of 212 grains! I would therefore expect a single mousegun rifle charge of 26.whatever to pick up only .1-.2 grains of humidity weight.

I've also checked this the other way as well-taking fresh out of the can powder and leaving it in the pan for days, 90-95 degrees F and humidity below 20%, and found similar effects with spherical powders, perhaps from loss of solvents. .1 grain or so loss for every 25 grains of charge weight.

Sorry, but I don't remember how the flake powders did--I just remember it might have been maybe four times as much weight pickup, don't remember the weight loss, if it even happened.

[Grump]

My Dillon seems to be doing better than an old Lyman 55, for 4064 powder. For spherical powders, it's always been alarmingly consistent--did I REALLY pour a new charge???? No change!!!
The charge bar returns by aid of a spring.
That's the old way, which I like better in many respects. Got the pulld-down rod to prevent stuck charge bar on the ram's downstroke? If not, I highly recommend it.

Dillon's newer system (I got it for one measure on a busted-repair call maybe 3 years ago) looses the spring and uses a two-part steel thingy attaching to the powder slide. It delays retraction of the charge bar until maybe halfway through the ram's downstroke, which reduces the danger of a double charge if you cycle the handle through shortstrokes at that part of the cycle.

It's just not as smoooooooth as the old springy thingy. I use the new for rifle loading, and the old springy one for pistol loads.

[DILLONHELP]

If you have the newer powder system, identifyable by the lack of return springs and the two-piece bellcrank, then be sure the blue wingnut at the bottom of the return rod is tight enough. Push forward on the handle, and while keeping the handle in the forward position, tighten the blue wing nut to a point where the coil spring above the blue wing nut is very compressed. This ensures that the powder bar is consistantly retracted to pick up the next powder charge.
Next, check the bolt that attaches the bellcrank to the side of the powder measure, to be sure it isn't too loose. Be sure that the little white delrin square that fits into the notch in the side of the powder bar is present, and not slipping out as the bar is actuated.
Finally, be sure cases are being flared at least .010". This makes sure that the powder bar is pushed all the way over, despite any minor differences in case length.

[pilot teacher]

Powder weight versus volume is not the same. Could be temperature changes increase the "volume" up or down. So while the measure throws the same volume it may weigh more or less. Just a thought.