After 29 years of shooting airguns I have found out several things.
1st thing I do now with a new airgun or a newly acquired used gun is clean and polish the bore. Run a few solvent wet patches through in a slotted tip and I am careful to prevent muzzle wear by not using the wrong rod (a subject too long to cover here) then a couple passes with a bronze brush and finally a couple dry to wipe the loosened crud out. THEN I coat the nose and sides of either the pellet or slug in a big bore with a bit of JB. I do about 40 or 50 pellets and/or 25 or 30 slugs.
And then I shoot the coated slugs and the polishing paste is carried down the bore by the bullet that acts as a lap. This will NOT wear the bore badly, just remove the imperfections that cause leading. Generally you only have to do this once in the lifetime of a gun, NOT every cleaning. Note: If you leave a moderator on you probably will want to clean it later, the paste ends up there, I usually take it off if it's removable. A few damp patches of solvent will clean out the residual JB and then I oil the barrel using Ballistol.
On a pellet rifle I test lubed pellets to see if they work, some rifles like it, some don't. I will sit watching a movie or something and using digital scales I weigh every pellet, discarding those that are too heavy or light. The last three years I've been putting 900 or 1200 pellets in a large plastic container and washing my pellets with (taking precautions for it's flammability, etc.,) 2cycle Synthetic oil mixed with E85 at 30:1. GENTLY moving them around so not to dent any. Pour them through a screen strainer and put the mix up till the next batch. This cleans the swarf/lead dust off too. Let them dry for a day or so OUTSIDE so the fumes aren't in your house or garage and the residue of the 2cycle oil will lubricate the cleaned pellets AND keep them from oxidizing if you don't shoot them up fast like I do. I've got sir rifles that have shot several thousand pellets and the bores are clean and no fowling and the accuracy is good. Only if the accuracy goes away do I clean again.
Shooting slugs in a big bore airgun is different - I ALWAYS shoot lubed bullets because of increased fouling and DO clean more often. But with a polished barrel it might be 400 or 500 shots before it needs it. (I've seen unpolished big bore airguns foul in less than 50 shots!)
For bench shooting I use different products: synthetic RC shock oil, FP-10, even transmission fluid. But because I don't want wet, slick, Trash attracting bullets hunting in the field with a big bore I want a dry lube. I eventually experimented enough to do this. I take my cast, sized bullets and put them in an old butter tub (50 or so) and put in 8 or 10 grains of Hexagonal Boron Nitride powder (ie: 'white graphite's) and then squirt in about a 1/2 teaspoon of FinishLine Dry bicycle chain lube and put the lid on. I then gently turn the container over and over for 8 or 10 minutes to get all the bullets coated. Then they get poured out onto a silicone baking sheet (but do NOT move them around, you'll disturb the coating!) and let them dry. Do this OUTSIDE so the solvent fumes evaporate where you will not breath them. Let dry for a day or so and the bullets should have a white powder coat that will stand mild handling and you can shoot a lot of them with no barrel fouling. It will wipe off but handled right it does the job.
Another way is to use 'Rooster Jacket' to thinly cost bullets (dilute with 50% water) and after they are dry then tumble them with a bit of the HBN powder. This makes a tougher anti-fouling lubed coating.
I've also had good luck for hunting accuracy but not match grade target accuracy with ONE. extra thin coat of HiTek bullet coat (but not good results with powder coat). I use 50% more solvent then the instructions call for and only coat n bake once for airguns.
