Case Lube & Powder Weight Check

[renaissance]

I load on a progressive rig (RCBS PiggyBack)
Although the RCBS Powder Measure (with a micrometer screw) has been extremely reliable and consistent for me;
I am in the habit of checking every 25 or 50 th drop with my beam scale.
Rarely has there been a problem of "shifting" drop.

Started reloading 357Sig for the first time recently.

Since I use all carbide dies, I never case lubed before
You have to case lube .357 Sig.

For the first time in memory my powder check weighings were drifting off.
I'd reset and a short time later they were off again.

It took a while to figure it out.
I lubed the brass by shaking it in a baggie with "One Shot"
The case lube was causing some of the fine powder (AA#5) to stick to the inside of the case and NOT being included in the measured charge.
They were comeing up short. (duhhhhhh)

After I took care to use a single UNLUBED case for the weight check, the RCBS Measure showed the charge to be consistently right on (again).

renaissance
(the rocket scientist)

 

[boing]

Yup. I use a bit of One Shot with my carbide dies to ease the press stroke, but with .44 mag and 2400 it was easier to notice. I dump the charge on the scale, tap the case base down on my bench, then dump again. That always gets the last of the 2400 out, but 231 sticks more.

You could always use a lube pad.