let me start out by saying that I'm new to pistols and chose a 19 gen 4 to pop my cherry and I couldn't be happier. I clean my pistol after every range trip and I have about 600 rounds through it, when I sat down to clean it today I dry brushed the bore then sent some patches soaked in hoppes no. 9 solvent through it followed by clean ones, the grooves in the entry side of the bore are clean and mirror like but as they get towards the muzzle have a gritty gunpowder look to them. So for the past hour I have been scrubbing and sending patch after patch soaked in no. 9 solvent through it and the clean patches are still coming out dirty with the gritty appearance still present. Am I losing my mind or doing something wrong? thanks in advance for any help/suggestions and I apologize for asking such a rookie question.