A bit off topic, but here goes.
Electrical equipment has some paper insulation, steel frames, steel cores, and copper/aluminum of course as the conductors. Some have cast iron in them as well. The oven is used to bring the temperatures to approximately 180 deg F and is held at that level for up to 20 days and possibly longer if needed, depending how wet the paper insulation is.
The process is very effective in driving out moisture, with no rust involved.
I do not dry black powder arms in an oven. I simply have them up to temp with the hot water, which aids drying, and then give them a good treatment with WD-40. I will see if I can get a picture of a 50 year old pistol bore and post, as that is how it and all my BP arms get cleaned.
Even if a metal gets flash rust, it can even be wiped off with a finger if accessible. In a bore, an oiled patch will easily remove it.