YOu can use the old favorite, Hoppe's No. 9 bore solvent, or Shooter's Choice( good to remove both lead and plastic) on a cleaning patch, run down the bore on a bore brush. Scrub it back and forth a dozen stroke. Re-soak the patch with more solvent and repeat. Then run a clean dry patch down to pull out all the lead and solvent. A couple of dry cleaning patches should clean all the solvent out, with the lead.
Then run a patch with a THIN coat of oil down the barrel to protect the barrel from rusting, and you are done.
When you take the gun out to shoot again, FIRST, flush that oil out of the barrel with alcohol. Pour out the alcohol and oil( the liquid will be light yellow in color) and then run a dry patch down to soak up the rest of the liquid alcohol.
The remaining vapors will evaporate, and leave the barrel dry.
I like to run a cleaning patch coated in a little wonderlube down the barrel because the wax holds the oil to the metal, for the trip to the range, or field. I generally stop short of the breechplug, as I don't want to shove any lube into the flash channel. Depending on weather conditions, and the length of the drive, I may flush that out also with alcohol at the range, or field before loading the barrel. Generally, on good days with reasonable humidity, I don't have to do so. My gun is transported in the back seat, with the muzzle down on the floorboards, and the stock up on the backrest. The gun is encased, of course. This lets any oil that might separate from the wax flow towards the muzzle, and not down into the flash channel where it can cause problems.