I keep my shop compressor drained on a regular basis for moisture and always blow out air in the nozzle before using, even checking what comes out blowing air on a flat piece of iron to check for moisture. I always hold a revolver looking into the barrel and turn the cylinder in bright sun or a light. If I see the small bit light that comes through the nipples, I'm good. Will check my long rifle the same way, holding a flashlight at the nipple end and looking down the bore for the small amount of light that can be seen from a clean bore. Can do the same with a flinter. Some may shudder at looking down the bore end, I don't store my black powder firearms loaded.
