Like Taylor, I use WD40 after drying with patches. I spray the WD40 down the bore until it freely runs out the vent or nipple seat. I am not CHEAP with it. I don't use a 'damp' WD40 patch for running down and up the bore. I buy it by the gallon and use a spray bottle that puts out good pressure - 4 to 6 sprays into the bore before I run the patch down. I want any and ALL residual moisture to be gone. That is what it's for.
I then use a dry patch down the bore which blasts excess WD40 out the vent or nipple seat. Up and down, up and down up and down - until I'm totally sastified all the rifling corners are well coated with a very thin film.
I use the same patch for wiping for wiping the outside of the barrel before putting the gun back together. I store them muzzle down in a rack. I don't have to check the bore in 2 days, 3 months or 3 years - it is without rust because it was clean before I used this very thin film producing oil called WD40.
I use moly grease on the bearing parts of my locks, inside and out. After cleaning them in a can of water (prior to doing the barrel) I shake them off, then either blow the excess off with mymouth if I'm lazy(most of the time), or with compressed air - then wipe with a towel - then liberally spray them with WD40 over the garbage can or gravel outside flushign off any residual moisture - it must work - none of my locks rust in 2 days - 3 months or 12 months. The air and WD40 does not wash or blow off the moly for at least a year's worth of lubrication. Good enough for me - I can lube once a year and be done with it - cleaning as noted.T
That's all the test I need. No special chemicals, no special anti-rust agents - all I've used for decades is WD40. I even use it on my modern guns as a wipe down- if I feel like it, mostly they are dry - except - I coat the underside of free-floated barrels and bedded action parts with moly grease. the grease doesn't soak through gun finish, nor does it soften bedding.
I normally use other chem.s. on modern stuff, though.