I broke-down the suspect over sized case loads I made.
I put penetrating oil in the cases to neutralize their caps so I could de-cap and resize them.
I cleaned them by hand with paper cloth and steel wool till shiny.
I washed them out in hot water and soap and let them stand in the water for an hour+ before rinsing them with hot water. I let them dry over night in front of a fan till they were dry on the inside then washed and dried them again. They were dry on the inside as I check each one with a Q-tip no moisture no grease was found.

I began to reload them and noticed as I charged the first case that the powder was sticking to the inside of the case. I put a Q-tip in the case and found that the powder (AA 2520 ball) seemed to be holding to the case by static charge. When removed from the case the Q-tip had many powder balls clinging to the cotton tip. When touched to the case the powder ball clung to the case. I used a Q-tip on some of the cases and again found the cotton tip coming out dry, but with a faint aromatic sent. Is the powder clinging to the case this way unusual? I did not load the case.

My guess ....residual penetrating oil. Penatrating oil by its nature will get into the pores of the metal and can be very difficult to remove. Soap and hot water may not do it. Use a Q-tip and rubbing alcohol

What kind of powder?
I've noticed that BL(C)-2 clings to my 35Rem cases no matter how clean and dry I try to get them. I also believe it's static of some sort.

If it is static ....roll the cases around in with a couple of used dryer sheets. Gets rid of static instantly.

In my opinion, don´t ever put any oils inside a case - very difficult to remove completely, and most likely the cause of the clinging powder. I have read other posts saying that oil is not a safe way to de-activate primers, either.
And, a metal case can not get "static" like plastic.
If you cannot pop the primer in a gun, you can carefully deprime it in your press with a decapping die and slow, gentle pressure. Protective glasses of course, in case the primer really goes off...
I've deprimed lots of cases this way.

Nope.... no such thing as a static charge on a piece of metal. Something else is making the powder stick.

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MikeG

Static charge on the powder itself?

Even if it did, the instant the powder touches it, the charge will equalize (because of the conductivity of the metal).

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MikeG

Just for the thoughts:
When I have oily/greasy hands and wash them with regular
soap, my hand keep allways a bit greasy/oily.
When I use "Detergent" (the stuff you wash your clothes in in the laundry machine)
My hands are mostly smooth and not oily/greasy at all.

So throw the cases in the laundry machine
and wash em....
(Wait for the wife to go shopping orso )

ciaooo

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Happy Loading, when completed --> happy shooting