Lee ProAutoDisk and Lee scale and Modern reloading dont add up...

[subierex]

I'm with others in this thread. I've found I have to go up at least one cavity size to get the charge weight listed in his manual. Having said that, I love Lee's manual and use it regularly with the knowledge that I have to start one cavity size larger than stated.

As always, I weigh the first charges until I get 2-3 that are consistent, then rock and roll, checking about every 50th after that. Note: I only load for pistol calibers.

edit: I should state that I currently use only flake powders: Titegroup, Unique, H110.

 

[SSN Vet]

My understanding is that VMD can vary slightly for the same powder from one lot to the next.....and can vary from the same jug with humidity.

My speculation.....Lee seems to be an advocate of volumetric powder measuring as "all you really need" for the average Joe to reload and save money. Hence, they sell three different volumetric powder measuring systems (dippers, auto-disk and perfect powder measure) and one "minimal" (though accurate) scale.

So, if VMD varies and you're not going to make extensive use of a scale, ya better be conservative on your published tables and use a light VMD.

No big deal, as others have mentioned, just start with one or two sizes bigger on your auto-disk, weigh the charge, adjust as needed and go to town.

I like to come up with the "average" charge weight thrown by my auto disk with a particular powder and then back calculate the density (I call it VMD*)and write that number on a piece of tape on and stick to the powder jug. Then if I want to throw a different load, I use my own VMD* to calculate the auto-disk size (in cc) I start with.

But then again, I r a geek engineer.

 

[CypherNinja]

I like to come up with the "average" charge weight thrown by my auto disk with a particular powder and then back calculate the density (I call it VMD*)and write that number on a piece of tape on and stick to the powder jug. Then if I want to throw a different load, I use my own VMD* to calculate the auto-disk size (in cc) I start with.

Have you ever had your calculated number drift over time? Or do the jugs just not last very long.

 

[SSN Vet]

Have you ever had your calculated number drift over time? Or do the jugs just not last very long.

unfortunately, my 1 pound jugs of powder last way to long (building an addition onto our house is putting a big crimp on my "fun time" )

and

yes, my back calculated VMD* has changed on the same jug.

I suspect this is either due to...

1) variation in the accuracy and consistancy of my scale and weighing technique.

2) variation in the volume of powder thrown (same powder, same disk).

3) changes in the environment (temp., humidity, static)

4) all of thee above.

In all honesty....just starting with one disk size higher than the chart works just as well. But doesn't satisfy my inner need to geek out.