I do a fair amount of firearms restoration as sort of a 'side job'. If it is a true collector grade, I limit my restoration to stopping any active deterioration, and applying the correct finish to any wood components.
That said, when working with a shooter grade gun, I really do enjoy taking one that has been badly damaged or neglected, and restoring it as close as possible to how it looked when new.
The Mauser 1914 pistol in this thread was badly water damaged. The grips were broken and growing mold. The frame under the grips was badly pitted. Additionally, there was light pitting across the rest of the visible surfaces of the gun. After letting the gun soak in Kroil for two days, I was able to knock the magazine out of the gun with a wood dowel and a hammer.
Since the finish of the gun was compromised by rust and pitting, there was not much point in trying to save the finish.
First picture is the gun components in a ultrasonic cleaner. It is being cleaned with a mixture of water, dawn dish detergent, simple green, and Lemi-shine. Lemi-shine is a mild acid (citric acid), and will remove any rust, along with bluing.
Pictures 2 - 4 are the frame, slide, barrel, and side plate after working with files and sandpaper to remove as much of the pitting from the visible areas as possible, while still preserving all of the proof marks and manufacturer roll stamps. The brown crud in the frame is sanding grit.
After the frame was sanded and polished as much as possible, the parts went back into the ultrasonic cleaner with a mix of water, dawn dish detergent, and simple green to clean and degrease the parts. When they were finished, they were stored in a container filled with denatured alcohol to keep them clean. Since I was going to rust blue them, they cannot be touched unless you are wearing gloves, or you will have a beautiful blued fingerprint in the metal.
Next Post Bluing.