I use stainless steel containers myself. Most are used food service heating trays and tanks that I got dirt cheap. I had a shop weld up a long tank from stainless stock and leak checked it but that is not used very often. I also use pyrex beakers and casseroles for small parts as they are sufficient for boiling water temperatures. Heck, you gotta refinish some small gun parts, just use a appropriately sized glass beaker and you don't use very much chemicals or waste much. You need a glass thermometer or electronic thermometer with stainless probe that goes to at least around 250F. to monitor the solution temperature for home use.
Your gun is like your nose, it is just wrong for someone else to pick it for you!