Micrometer for auto drum

[James Hensler]

I have seen a pic of one from this site! Who makes one

[Ranch Dog]

I look at every post on this forum and I don't remember seeing one.

[James Hensler]

Look at the pic on
Auto drum with Rifle Cases
I see it’s your post so it must not be but
Man that looks like a Micrometer

[larryw]

Looks like an extended adjustment key, haven't seen or heard of a micrometer
adjustable AD ??

[James Hensler]

I took apart a perfect powder measure and removed the metal tube. Of course it is a different size but I have no doubt the someone can use a 3D printer and make one

[Ranch Dog]

Look at the pic on
Auto drum with Rifle Cases
I see it’s your post so it must not be but
Man that looks like a Micrometer

I cannot find the post but it is probably the Deluxe Perfect Powder Measure. Honestly, I use the standard Auto drum exactly like a micrometer, you just count the key turns. One revolution is a 1 cc and each facet a tenth.

I have a downloadable spreadsheet (open office format) on the forum's server: http://ranchdogoutdoors.com/Reloading/Downloads/

One of the features is an Auto Drum Charge calculator. It even indicates whether a small or large drum needs to be selected. It is very accurate if you determine the VMD of your powder and enter it for the powder choice ("Powders" tab).



With the example above, using a large drum, you would zero the drum. I hold it up where I can see the radius of the drum and then bring the plug out where it is flush. The setting would be 21 complete turns of the key and then nine facets (one reference short of a complete turn). With your powder lot specific VMD, it will be very close to the charge you are looking for.

[larryw]

Look at the pic on
Auto drum with Rifle Cases
I see it’s your post so it must not be but
Man that looks like a Micrometer

Is this the photo you are referring to?
It is the one I said looked like an extended
adjustment key??

https://www.lee-loader.com/viewtopic.php?f=20&t=2169

[James Hensler]

Yes

[Ranch Dog]

Straight up Auto Drum.

[cj8281]

But now I have a question,

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.

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. I can understand running the case up at the same speed so the drum turns at the same speed each time which might affect how the powder reacts when the drum starts moving. On my auto drum, with a flared case or unflared case, the drum performs a full drop, the rotation is the same.
Please explain.