I shoot a lot of trap and know exactly what is happening. To get rid of that gunk do this it really works. Get a good wire brush, cut a 1/4 inch strip of scotch-brite pad. Run the strip of S-B pad around and up the wire brush full length leaving some exposed areas of wire brush. And push it in firmly so it doesn' t come off while cleaning. Take off your barrel leave CHOKE TUBE IN and use something like a margerine container to protect floor. Get some LIGHTER FLUID, insert the wire brush on a cleaning rod and run lighter fluid in until it runs out other end of barrel I always clean from the chamber end. Srub the barrel hard and add more lighter fluid as needed. Leave set for about 15-20 minutes. This gives the lighter fluid time to dissolve the gunk. Wet cleaning patches with LF and the 1st few will be black as coal. keep running patches until they come out clear. Bob[8D]