I think he got enough answers to solve his problem.

It's either go off topic, or let the thread die. We're keeping it bumped up.

I have a MLer that has a regular Blued Steel Barrel that no matter what I do I still get a light brown colored patch from it after it's clean. The Bore is sh shinny and clean that it would blind you yet I still get that light brown colored patch.
If I dont have time to clean right away I Always run a Oiled Patch down the bore, using a alcohol patch dries it up. Also some oils cause a reaction to the steel in the barrel, so sometimes what you think is rust, sin't.
(BP)

I've yet to check it today, but I finally got clean patches yesterday. I'll check it again today and again in a few more days.

I was just concerned that maybe I had more than surface rust, and wasn't sure what I'd do about it or how to know the difference.

I'm chalking this up to a lesson learned. No matter what clean it ASAP! If you won't have the time to clean it that day don't shoot it!

That's probably the best thing to do. In my case a delay in cleaning was not the cause of the brown patches as I cleaned it right after a range session. I believe it happened because I poured boiling hot water down the bore to flush it out and so the moisture would eveporate quickly. I believe that for some reason the boiling water caused a bad reaction with the metal. I can assure you I'll never do that again.

Boiling water has been known to give some surface rust. I beat the problem by putting a little Ballistol in the water when I flush.

That is a very good rule to live by, and especially on a blued rifle. Now, based on my experience (semi :D) if you have a true stainless steel barrel, it is WAY more forgiving. I still try to clean my SS guns asap, but I'm not worried if for some reason I can't get to it for a few days. NEVER had an issue on SS, and I shoot pyrodex.

I believe you're right Muley, I have experienced "flash rust" over the years past when I used to flush with boiling soapy water and then rinse with straight boiling water. Nowadays when I've finished shooting I wipe the bore out with a few patches saturated with Butch's Black Powder Solvent (or similar) to get the heavy fouling out and then flush with warm tap water and Dawn dish soap. I then flush several changes of clean warm tap water through the bore and begin drying the bore immediately after I'm satisfied there's no soap residue left. I then plug the touch hole or nipple and pour a few tablespoons of 91% Iso Alcohol in the bore and with my finger over the muzzle, I tip the barrel back and forth a few times and then pour out the alcohol. I push a dry patch down into the powder well area and tamp it gently with the rod and then leave the barrel stand muzzle down for a few minutes. The alcohol picks up any remaining moisture from all the little nooks a patch can't get into. I fish that patch out with a worm and dry the bore with clean dry patches. Wipe the vent/nipple area clean with cotton swabs and run a wet patch of ballistol or barricade down and out. Wipe the outside off with my oil patch and done. I know it sounds like a lengthy process but it's not bad and I have never had an issue with "flash rust" since.

BPS

Checkout automotive fuel line deicers if you want an 99% alcohol. Its relatively cheap and its available in methanol, isopropyl and occasionally isobutanol in aviation applications.

Ballistol contains a little isobutyl IIRC, adding a little more ISO to it for swabbing after flushing with hot water should help reduce flash rust. The extra alcohol should mix with the water and help it evaporate more quickly and then leave the mineral oil behind.

Wrap a bore swab with 0000 steel wool amd lube your elbow. Rust will be gone, and you will have a polished bore. Apply oil after you are done.

Muley, interesting test. I'm already sold on Eezox and the test again bears that out. Problem is it's somewhat expensive, so I may try the Ballistol. One question - Ballistol comes in both spray and liquid form. Which do you recommend?