Leading in the cases?

What's going on in the photos below? Most of my 38 cases come out like this after shooting them. Load is 2.7 WST with 148gr HBWC. Is that lead that gets deposited on the inside of the cases? The grey/white stuff is only at the top, and never below where the bullet would have been seated. I wash my cases with dish soap and warm water before reloading, and it doesn't get rid of it. Doesn't seem to affect anything; I'm just curious as to what it is and what is causing it.

Probably a touch of lead.  The bullet is expanding as it leaves the case and is wiping off.  

Tru a 50/50 mix of white vinegar and 3% hydrogen peroxide and see if it will remove the stain.  That will remove lead.

Wobbley, when applied to the residue, that mixture started foaming and shortly after it has dissolved all of it. It was a fun alchemy / black magic experiment; thank you for that.

Careful with handling the liquid when finished. It now has lead dissolved in it (lead acetate I think).

Can you soak barrels or cylinders in this stuff ?

I was careful not to get the liquid on my skin. The thought that it contained dissolved lead did cross my mind. While one may be tempted to tumble cases in this liquid to get them clean, it seemed to attack the brass and I tossed out the case I used for the experiment. Steel in barrel may be ok.

Vinegar = dezincification of brass.

Lead is my guess? Check scale with test weights. Lower powder charge a tenth or .2 grs.

See posts by "unclenick" https://www.thehighroad.org/index.php?threads/cleaning-brass-using-citric-acid.708100/page-2

Multiracer wrote:Can you soak barrels or cylinders in this stuff ?

Don't use this mixture on a gun you like, only a junker. I think it's corrosive . It might be OK for stainless.

Have you ever chamfered the inside and outside of the case mouths?
Actually, the bullet and case are expanding as soon as pressurized.

I never chamfered pistol cases. That would probably help if the lead was right at the rim, but it collects quite a bit down as well. Coating the bullets in alox would likely solve this "problem". We'll see how it evolves after many reloadings.

If you're getting good accuracy with minimal barrel leading, I'd forget about it.