Take a .40 caliber or .30 caliber cartridge brass. Take some Brasso and polish that casing end to a high shine. Be sure and take some tape and wrap the end where you would load it from, to cover sharp edges. This can scratch your barrel if you leave it plain. Or you can take some simple tin foil and roll that into a ball SMALLER THEN THE BORE of the rifle you want to check. Make sure it is small enough to drop in and roll right back out. Just drop that down the bore, then hold a flashlight to the side of the muzzleand shine it down the bore. The light will reflect off the metal objectin the bore and illuminate the barrel for you to check for dirt, rust, etc. In a .54 caliber or bigger, go to Wal Mart and in the flash light department they sell a "pen light" flash light that is small enough to turn on and then slide right down the bore. The one I have will not make it down a .50 caliber but I am always on the look out ofr one smaller.