Think about the "pores" in the metal....ie clean a firearm after a range day, clean it till ya get clean patches visable......next day run a patch through it.....dirty black carbon, etc etc ....
My CHL rig gets cleaned three days after range day.
Check it out....and let me know what ya find !....:o)
Three days later? I'm not quite sure I'm following you here. But you've got a GOOD point about the pores in the metal. We started using Kroil-Oil when I shot with a bunch of 1000 yard shooters a couple of years ago. You clean...and clean...and clean....until the patch is clean. Then wait an hour, run another patch with Kroil on it thru the bore and it comes out as if you had JUST fired the thing!