I get stuck on crud like you mention, on my Ruger MkII... I soak it with solvent, and use the tip of a small screwdriver to gently scrape it off. If you go easy, and don't apply too much pressure, you will take off the deposit, and not hurt the gun. I do this only on smooth steel surfaces... I wouldn't recommend it on a matte finish, or a blued surface. You might try a nylon bore brush with stiff bristles.. shouldn't hurt the blued surface, but would be better than a toothbrush..

"Progress, far from consisting in change, depends on retentiveness..those who cannot remember the past are condemned to repeat it." Santayana