Not rare, but they don't come from the factory that way either. Those are plain old stainless SP101's with either custom finish jobs or--much more likely--owners who spent a great deal of time on them with a Dremel tool and polishing compound. Some people like the look, some don't.
Hey Buckeye63 - I was pretty much in step with the idea that what you saw was somebody's own polish job. But I did look it up in a reference book and the possiblity does exist it could have come from the factory that way. Very small production runs have been found in various calibers with numbers estimated to be 100 units to 1,500 units per caliber. If you had the box you could see the catalog number on the label and if it starts with GKSP it would be a gloss SP. I'm guessing the shop doesn't have the box? Next option would be to request a letter from Records Department and they would be able to match serial number to catalog number and tell you if the gloss finish was factory.
In all liklihood it is not factory. But you won't know for sure unless you see the label on the box or ask Ruger. If it is a factory gloss finish it would be very rare.
I polish the sides of hammers and triggers ,but that's to reduce friction. I decided to polish the "bare" sections of a couple Tops knives I own.Hoping that a polished surface will reduce areas where moisture can be trapped and oxidization can start. I'm a function over appearance kind of guy though.
Try this "Renaissance Wax". Heard about it few years ago. Only imported from
England at that time. Probably available here now. A little expensive. Hand polished several SS handguns including SP101. (Lots of spare time). Used the wax, no fingerprints. Have since used it all of mine. Leaves no prints after handling. Works great on blued, even better. Used it on .357 deep blue Python and leaves no prints. Works great for me. Google it. Used in European museums for protective coating. Waxed several firearms and still protected, no prints after 2 years.