Lee Auto Disk Powder Measure

[Shooterjim]

I'm having trouble with my powder measure.

I had a Hornady Lock-N-Load Powder Measure and now I'm using Lee Auto Disk (both on a Lock-N-Load progressive press). I'm using Hogdon Universal in both and have been having inconsistent loads in each.

Why the inconsistent loads? I thing I've tried everything but I'm looking for suggestions.

[ranger3]

What is inconsistent? My Lee powder disk with Bullseye is never off more than .1 grain. But I would agree that the better the powder flows the more likely loads are to be right on.

[Fishslayer]

Have you tried running a half dozen cycles or so before actually loading?

Sometimes you can get changes in charge weight as the powder settles in the hopper.

What are you weighing with? Electronic scales can drift & interference from flouro lights & such can cause problems. Electronic scales also need to stabilize for awhile after turning on. I just leave mine on all the time & calibrate often. Scales should also be located on a surface isolated from the vibration of the loading bench itself.

[sofbak]

Because of the design of the Lee auto-disk, it will inherently dispense a smaller load than the published data in the lee instructions. This is due to a phyisical characteristic of dry bulk materials called the "angle of repose". Google it if you want to know more.

Depending on the powder, my auto-disk would under-deliver anywhere from 5% to 16%. Unique was the worst, trail-boss was pretty good, and w231 has been the most consistent. From this, I can postulate that Unique has the highest angle of repose, trail-boss had the medium, and w231 has the shallowest angle of repose.

Mechanical disturbances to the press during operatiions also affects consistency of delivery, as the disturbance will affect this "angle of repose" that I mentioned earlier. Essentially, the less disturbance or jostling during operation, the smaller the load, more disturbance "settles" the powder into the cavity, and thus a larger load. And if your motions and magnitude of hand force vary from stroke to stroke, the more variances you will get.

I switched to the adjustable Lee bar and seem to get more consistent results for throw-to-throw. Also, I was able to dial in much closer to the desired load, whereas the disc has fixed volume increments that were not always the load I wanted.

I have read on other forums that some reloaders have attached a small aquarium pump to their powder bin to provide a consistent mechanical agitation, and thus a consistent settling of the powder in the auto-disk hole. I just went with the adjustable bar, and concentrated on consistent hand motion during the entire process.

[stilly]

You can tape a vibrator to it too but make sure it is painted black for tactical reasons.