Is it the powder or the copper that attracts moisture and causes corrosion?
Just wondering because I sometimes only run a handful of rounds through my rifles and living near the sea they start to rust if I don't clean the bore.
If it is only powder fouling, then would hitting the bore with something like Hoppes or other powder solvents keep the rust at bay?
robz

When you fire a rifle, the heat of the burning propellant removes all protective oil. Neither copper or powder fouling have anything to do with it. It is the bare metal left behind and any moisture in the air - and there is a lot - will condense on the metal. Simple answer - oil the barrel after firing - Hoppes etc.

So just running an patch with oil through the works will keep it happy until the next outing?

Yes. The Australian Army and for that matter, all Commonwealth Armies were - rather insistent - that the barrel be 'lightly oiled' after firing. I will not go into the brutal and uncaring methods they used to enforce this - suffice it to say that it works.

Here is what I do if I have fired a few rounds, and do not want to clean the rifle, as I am still on a hunt.

I will use a Bore Snake and pull it through the barrel 2 or 3 times.

This gets out all the "big chunks", so there is less debris to attract moisture.

If I am in a wet climate then I swab the bore and chamber with Prolix. Then dry it out.

I have found that Prolix does not effect the impact of the first rounds out.

If I am not going to hunt with that particular gun for a day or two I just leave the bore chamber wet with Prolix. TYhen I dry it out before I shoot.

his is not pretty but I have this stuff with me all of the time in my shooting box. This box contains everything I will ever need when shooting competitions.

With barrel pointing down hose out chamber and tube with brake cleaner then while that dries out (help it with can of compressed air—also can be used to blow out the excess oil in the bore) get out the Breakfree and then hose it down through the chamber---let it drip out. Then I will put a rolled up patch in the muzzle to keep any excess oil from leaking out if you do not use the compressed air.

It I have time to get the rods, bore guide, brushes, jags out then I will just clean it but this works in a pinch until I get time to clean properly. DO NOT stand the rifle up in the safe doing this---oil follows gravity.

quote:

Originally posted by robz:
Is it the powder or the copper that attracts moisture and causes corrosion? ...

One of the Physics Laws has to do with Environmental Conditions always attempting to reach Stasis - a balance point.

When you shoot the firearm, all the moisture is removed due to the Heat. As the firearm sets, the Environment trys to reach Stasis and the Humidity(Moisture) migrates into the Powder Residue to elevate it's "dry" condition.

Once the Moisture is in the Residue, the Residue acts as a Dielectric and allows a small Battery to begin working between the Barrel Steel and the Copper. This ALWAYS happens when two dis-similar metals are separated by a dielectric and moisture is induced. Same reason we have Sacrificial Anodes on Boats.

So, the Battery begins transfering metal from the Barrel Steel toward the Copper and Pits are created.

The addition of the Oil which Kim mentioned, "Seals" the Residue from the Environment and the Moisture can not get past it.

However, as usual, there are other things to be concerned about when adding the Oil/Grease/Lube. If left in the Bore, depending on how much remains, it can act as a Bore Obstruction and Ring a Barrel. So, it is a real good idea to follow the Oil with a couple of Dry patches to remove any excess.

Best of luck to you all.

HotCore has stated it far more scientifically than i could, but he is right. A barrel fired until hot in an environment with humidity will attract moisture and because the oil is all gone, it will rust. I see it a LOT with shotguns. Guys go out in the morning and around here there is often light fog in bird seasons. Shoot the guns till they get hot, put em up in a softcase or sock, then the next time the shoot, the shells wont extract easily. The chamber is all rusted and the brass base drags on the corrosion. A couple patches with solvent, one with oil, a couple dry ones after shooting will do a great job to stop the rust. The main point is getting some protectant back in the pores of the steel.

I'm really lazy about cleaning my guns. I live where the humidity is usually pretty low. We call 25% RH a "humid" day here in the desert a bit east of Reno. I always have my A/C running in my house. Am I in danger of pitting the bores of my chrome-moly ARs? I have a few guns with stainless barrels. What about them?

Not exactly on subject but I find that while I'm still at the range and the barrel is hot, if I swab out the barrel with Kroil or Hoppes, it is much easier to clean later. I really put the Kroil to it. Using a patch that is soaked with that or Hoppes. I do not swab it out.
Then, if I'm feeling lazy, I can let the rifle go for a couple of days before cleaning it and the crud seems to be still soft.
As Hoss sez, if you put the rifle in the safe with a wet bore, be sure and put it muzzle down.

Living in a cool, wet climate, it is often raining when I go out in winter - like now - so to solve the problem I create a 'waxy-lube' wad on the base of the bullet by dipping it in the molten lube. This coats the bore and internals of the suppressor and prevents copper fouling at the same time. All I have to worry about is the externals of the gun which I treat with Rapid-Tap cutting fluid. This stuff also works in the bore and is a good cleaner. It's a bit expensive!

Hey HomeBrewer, It sounds like you are fairly Safe from corrosion. The problem then becomes the "mind-set" of being somewhat Safe, which results in a justification process of delaying or just not cleaning. Then it becomes a Habit and eventually they never get cleaned.

Chrome Bores are difficult to screw up, so is stainless. But, stainless can become damaged, just slower than constantly rusting Blue Steel.

You can clean the Deer before cleaning the Stainless Deer Rifle - as long as - there is no blood on on the firearm. Blood will damage the Stainless used in firearms fairly quickly. I have a Ruger Target Security Six that I touched the Grip area with Deer Blood on my hands. Didn't notice it until the next day and by then the Stainless was "etched" where the blood reached between the Hogue Grips.

quote:

Originally posted by robz:
Is it the powder or the copper that attracts moisture and causes corrosion?
Just wondering because I sometimes only run a handful of rounds through my rifles and living near the sea they start to rust if I don't clean the bore.
If it is only powder fouling, then would hitting the bore with something like Hoppes or other powder solvents keep the rust at bay?
robz

As HC pointed out it is the dielectric set up between the copper and the iron in the steel with the residue being the medium, activated by moisture. Your wildcard is the salt content of the air. That sets up a more potent galvanic action and worsens the corrosion.

Several years ago a fellow hunt club member asked me to check out his Rem. 700 ADL, .30-06 because it wasn't grouping well. One look down the bore revealed clumps of copper verdigris and a lot of carbon fouling. He had owned the gun for 10 years and never cleaned it! Only factory ammo had been used in the gun. But, it had been kept indoors in an air-conditioned environment. It took two weeks of Hoppes #9 soaks and brushing plus Remington abrasive bore cleaner to get it down to steel. Everywhere there was a clump of verdigris, there was now a nice big rust crater. The gun got it's accuracy back, but it fouled quickly. Had he just kept the bore oiled(to eliminate the oxygen), he could have reduced or prevented it.