Re: Micrometer for auto drum
Posted: 28 Jun 2020 05:21
Ranch Dog wrote:Straight walled cartridges that are going through a Powder Through Expander die need to be resized and re-expanded for every cycle of the Auto Drum during setup or the dispenser will progressively drop smaller charges and you will find yourself constantly adjusting it a facet at a time. If you don't adhere to this procedure, the first time a "clean" case is run through the measure it will be overcharged.
You are not changing the volume that is collected in the drum's chamber; rather, you are changing the arc of rotation and the ability of the drum to deliver that charge completely.cj8281 wrote:But now I have a question I don't understand how the expanding die is going to change the volume that the auto drum is going to drop. The volume is set by the plug, running a case up actuates the rotation of the drum.
Each additional pass of a case through the Power Through Expander Die, without the case being resized, see's the case expanded further. In effect, it shortens the case, leaving the Auto Drum less length for drum actuation. A short walled case, say a 45 Auto, has only a minimum length to articulate the drum fully, to begin with. Successive passes of the same case through the PTED is no different than backing the die out of the press. With the range of actuation less, the drum's chamber does not completely dump—less case length each at each actuation, the less powder that falls each time.
There have been a couple of posts here about a reloader constantly adding a grain of powder adjustment on Auto Drum setup. Actually this is not something new as the Auto Disk experiences the same issue, but with the inability to resolve the volume of the drop in that the disk is fixed. That is where this knowledge came from for myself and others. A fresh case with every adjustment cycle, like would be used on a reloading cycle, is the fix.