Ruger pistols, rifles and shotguns have always been hot caustic blued, except for the infrequent rust blued semi-custom job.
Refinishing quality is something like 95% polishing work and 5% bluing. In other words, the bulk of the work and effort is in preparing the metal and polishing it. Unless you have access to hot caustic bluing baths, and are practiced at using them, it is an AWFUL LOT OF WORK to get into for just a few guns.
I got into it many years ago with no experience or preparation. Just read the gunsmithing books, particularly the Brownell Gunsmith's Kinks series, procured the chemicals, made my own tanks, and had at it. Over 20 years later, I have to admit it is a lot of work and effort. You have to be a serious hobbyist or intend to go professional to make it worthwhile.
The hand polishing is not technically difficult, just tedious.