The above recipe has been around a long time. Many call it Ed's Red. Works as well as Kroil. I use it for many things including loosing up stuck threads.

Many people shudder at the thought of water on their guns. While leaving water on them is not good, real hot water, warms up the gun enough that any small remainder will quickly evaporate unless some gets trapped. Hence, the oven trick it will cause any trapped moisture to steam off. 350f is well below the temperature that will effect any tempered parts. My dad was into muzzle loaders big time and taught us to clean out black powder barrels by removing from stock, take off nipple and stick breech in bucket of hot soapy water then run a patched jag down the barrel and it would work as a pump and suck the hot soapy water up and down the barrel as you swabbed and get it clean. Then a couple dry patches and then one with a bit of oil.