Changes in dropped powder weight with 550.

[Holshot]

I use a Dillon 550B, RCBS Chargemaster digital scale, Clays powder for .45 reloading. When I'm loading I check random drops and they're always right. However, when I go back to the bench several days later, the powder drop is always a few tenths of a grain off from where I left it. I always empty the powder measure at the end of a session. I always calibrate the scale before I check the dropped weight. And I always spend a good amount of time getting the weight back to where I left it a few days before. I store the powder in its original container in a controlled climate, however, the press is in the garage and does go through some temperature changes. Easily corrected I agree but I am curious as to what's happening. Any ideas?
Thank you

 

[1911user]

It takes several powder measure cycles to get the powder settled in the hopper again. This can happen even if you leave the powder in the measure and come back several days later. Throw 10-15 powder charges to get the powder settled then start weighing the charges. I think you'll find it is consistent again.

 

[Holshot]

Thank you.

 

[loadedround]

1911 User is a 100% correct and his advice should be a rule of thumb with all powder measures not just Dillon.

 

[HSMITH]

With Clays in my 550B's I could almost calibrate a scale it is so consistent, but only after 20 rounds or so. The shaking of the press and so on settle the powder somewhat in the hopper, once it settles out it is rock steady.

I drop 15-20 charges, start loading with all stations full and final tweak charge weights over the first 10 rounds or so.