It's been my experience that it's hard to align my eye when I shine a flashlight down the barrel to check it's cleanliness, and when I slide a bobber light all the way down, it is just too bright to be useful as well. I took an unmentionable cartridge case (.38 spl) and on the case head, stuck and then trimmed, a highly reflective silver piece of mylar from a AAA bumper sticker. Just slide the case down the barrel, hold the flashlight a few inches back from the muzzle, and you can easily view the condition of the rifling w/o having to keep adjusting your eyes. Like the three bears and their porridge - not too bright, not too dim, juuuust right.