That's really strange. Is that to remove the rust without having to scrub it with steel wool?
Not that I won't try something new, but it seems like I've tried everything.
No pyrodex has been used! Only BP
I live in Utah and it's not particularly humid in my house.
I have no issues with any metal objects rusting in my garage and some of our laundry is hung there to dry. I don't store my gun out there.
I have zero issues with rust on the outside of the barrel and my lock.
Here's my process in case you're wondering.
Clean asap. In some cases I might have a couple hour drive home before I can clean it but so so immediately when I get home.
Take barrel out. Rinse with cool water.
Fill up bucket with clean cool water and put a really tight patch (2 patches) on the jag and work it up and down the bore for about 5 minutes with the breech in the bucket.
Use 2 new patches and do it again.
Rinse a couple times with clean water ( I've tried distilled also)
Dry bore with 2 patches, replacing the 2 patches a couple of times.
Douse it with WD-40, in the touch hole and down the bore. 1 patch up and down a couple times to make sure it's coated and squirt oil violently out the touch hole.
Sit barrel bore down for a couple hours.
Patch out the wd40.
Use CRC sp-350 in the bore for rust protection.
I have tried acetone and alcohol after dry patching to help dry it. I've tried a bit of soap when cleaning. I've tried hoppes BP cleaner.