This makes it possible to use a progressive reloading press with a separate powder-measuring method, such as an auto-trickler. Hornady makes a "Powder Funnel Die" to solve this problem, but it's not case-activated: you have to pour in the powder while the press ram is at the top of the cycle.

I designed mine so that it is case-activated. You can do all the of the manual steps at once, while the press ram is down: insert an empty case, place a bullet, and put a measured powder charge in the dropper. Then cycle the press.

I've designed two "powder sleeves", one for longer, large-calibre cartridges, and one for shorter small-calibre cartridges (similar to Powder Sleeve #1 and #2 that come with Hornady's case-activated powder drop.)

Printing Notes

The "retaining clip" is pretty intricate. Your first layer has to be dialed in well for this part.

The plug can be printed on its pointy end, with supports, if you sand it smooth after printing. Or it can be printed right-side up, but it will need a decent-sized brim for bed-adhesion.

The plug needs to have a bit of weight to it, to ensure it closes after dropping a powder charge. I have two versions of the "plug" part. One is solid, and can be printed with 100% concentric infill. The other is hollow, and you can print it with a pause to add some ballast inside before the print finishes. I used sand, poured in with a small funnel.

After Printing

The powder sleeve will likely need to be wet-sanded a bit, until it can slide freely inside the die body.

Also, if there's any stringing inside the powder sleeve or die body, you'll want to clean that out so powder grains don't get snagged up.

The threads may give you trouble. I found the printed outside threads on the die body worked with Hornady's Lock'n'Load bushings with no difficulty. But with the printed lock nut, they jammed up hard. I found it necessary to wet-sand the threads on both parts pretty good before they would work smoothly.