In the 18th century and the early days of the 19th, the seagoing war ships had a problem of what appeared to be a perfectly fine cannon that would with a normal load blow up, destroying the gun and a few bystanders who loaded it correctly. The problem was caused by some water getting into the metal of the cannon and starting to rust. The rust would eat in a number of directions causing greater weakness in the metal that was thought to be solid.
On page 80 of my book I have printed a picture of an iron molecule enlarged 50,000 times. It looks like something in a playground that is far from solid. If you short start a patched ball 6 or so inches down the barrel of your rifle and fire the rifle you will very often create a bulge in the bore. The bulge seldom shows up on the outside of the now ruined barrel. If the steel is so solid, where did the steel that used to occupy that space created by the bulge go? It got squished into all those steel molecules.
We often hear: “I cleaned my barrel with good hot soapy water and wiped the barrel clean with white wiping patches that came out spotless. Then a few days later, if I run a dry wiping patch down, it comes out a rust colored orange.
I know that water will rust steel but that bore was bone dry. Where did that water come from?” It came from all those spaces among the steel molecules where you put it. If you finished with a nice light coat of oil after your cleaning procedure to seal out any outside source of water or just humidity to stay out, you are also sealing in the water you put there with the hot soapy cleaning method.
I think you could put up with this small rust problem for quite a few years BUT on the other hand, that small rusting isn’t strengthening your barrel so why put up with it?
What I accidentally developed was a system minimizing the use of water as much as possible. Wiping the barrel with a wiping patch only damp with your favorite Moose Milk. Squeezing that patch in a vise could not produce a whole drop of liquid. The dampness will penetrate the residue which bakes on the corrosive residue and sweeps it from the barrel. Make sure you are pulling a snow white clean wiping patch before you then coat the bore with patches wet with WD 40, making sure all surfaces are coated. If you have a barrel protector on your ram rod, leave the ram rod with its WD 40 patches in the barrel till the next time you go hunting or to the range. Drop 30 grains of whatever down the barrel on the new day and fire that bank down range to burn off the WD 40. Give it a wipe and load for your first shot. By storing with this water displacing oil you will soon fill all those molecular spaces withWD 40, and water and residue just can’t get in there. If you have a better penetrating water displacement oil it should probably work as well
Sometimes you will pull black residue a few days after cleaning. Treat it the same way as water caused rust.