Hi guys, new to this forum.
My new solution to rusty anything is an electrolic setup.
Google it if you need details, but here is my reason for using it.
(1) You can make it small or large.
(3) Not only removes rust but deposits a nice black oxide coating that holds oil.
Only problem I ever had was leaving an M1 Garand barrel in too long.
It was flaking in places, and the process took off the date stamp (12-41)
It is especially good for stuff like mags as they are often overlooked in the cleanup process, and the electrolisis does such a good job.