Taylor and big Ron here had similar experiences with using straight Ballistol inside and out.
Both guys had rust, inside and out come the next morning. Granted it was fairly humid in both instances.
Considering Ballistol will mix with water, ie: is water soluble, how can it prevent rust?
Dphar alluded to this FACT in a similar discussion here - same subject, years ago.
I would prefer to use an oil that will not mix with water, in fact repels it. Ballistol does not nor will not repel water, imho.
Yes I know guys use it - I will not. I use water displacing or repelling oils. I have never rusted a barrel. Both Taylor and
Ron had never either, until they tried Ballistol.
I saw what came out of Ron's barrel and it certainly appeared to be rust to me, no different than many ML's that come into Taylor's shop - pitted bores and rust.
After drying my bore and outside of the barrel after cleaning, I flush the bore with WD40 then patch that, blasting WD40 out the vent or nipple seat (barrels off the gun), then wipe
down the outside and reassemble. I have never rusted the outside nor the inside. I do the same with the locks- hose them off with WD40 after drying- shake of blow off the excess and reinstall.
The moly grease I put in the internals stays for almost a year, likely 20 cleanings, sometimes more, then gets replaced.