Do not ever use anything containing chlorine in any form to clean your rifle. Not toilet bowl cleaner, not bleach, not anything containing HCl. It is all very corrosive to steel, worse than corrosive primers, and is difficult to completely remove from the crevasses in the breech plug and drum or touchhole areas. It is still corrosive even after you neutralize it with baking soda. Warm, soapy water always worked just fine for me for general periodic cleaning. If you need to remove surface rust, or worse corrosion, use a chelator like Evapo-Rust, but be careful, it might take some of the brown or blue color off the outside of your barrel. HCl can also do this, so you can get better results with the safer product.