PS: I clean after shooting w/hot soapy water, rinse w/hot water, air dry. After drying, I use a Bore Butter patch to lube the barrel but dry patch clean the barrel before shooting(4-5 patches).
If I'm doing something/anything/everything wrong please let me know.
Almost guaranteed you have BB residue in the flash channel.
No need to use BB after cleaning.
A dry patch with one or two drops of gun oil, 3 in 1 oil,or sewing machine oil
is plenty. all you need is a very fine film coating the bore.
As I mentioned earlier, no need to waste a cap.
pull the clean out screw if yours has one and /or the nipple swab out the channel with alcohol with a pipe cleaner. I do this after cleaning anyway,
Have never had a rust issue in 35 or so years.
When I go to shoot, I dry swab the bore 1 time, load and shoot.
I have several times, just loaded and shot.
Trick is, my bore and flash channel are NOT drenched in lube after cleaning.