I don't know the process to clean a tarnished firearm. However, if it is a very old one, or you think it has historical and/or monetary value, DO NOT ATTEMPT TO CLEAN IT. This can cause trouble in dating the weapon and will drastically lower its value. Collectors and appraisers like old, historic firearms as-is, with tarnish, rust and all.
One way of cleaning without damaging is to clean with 0000 steel wool and gun oil....
http://home.howstuffworks.com/how-to-clean-furnishings3.htm
no
you use baking powder and coke
One suggestion is Lemon or Lemon rinds
I haven't seen vinegar clean jewelry but I saw my girlfriend clean my tarnished earrings with toothpaste. I was amazed.
Rubbing it gently with sodium bicarbonate.
The acid in the drink gets into the tarnished or the dirt particles and will clean it but you might have to leave it in for a few days.
It is tarnished, but not ruined. Clean/polish it as you would with a polishing cloth, or bring it to a jeweler. It will be fine.
Tarnished stainless steel flatware can be cleaned with warm soapy water. For tougher stains immersing the flatware in boiling water will remove stains.
You can clean a tarnished metal frame of an old vintage purse with baking soda and water. Make a paste out of the baking soda and water and using an old toothbrush, scrub the metal frame of the purse gently. Wipe away the residue with a clean, damp cloth.
Mix salt and vinigear, and soak it in. But if its valubale, DO NOT USE TOO MUCH SALT.
put in a glass of cheap coca cola and leave over night