A couple months ago I picked up two pre-model 10s. One was in pretty nice shape and dated about 1948, the other wasn't so pretty and dated about 1952. In the picture it doesn't look so bad, but it was probably at about 50% bluing and had some rust pitting, but the barrel wasn't bad and the lock up was acceptable. I decided to clean it up a bit and refinish to better protect it.
This is the only picture I can find from before, which is obviously after I disassembled it. The picture makes it look better than it really was.
I stripped it down to bare metal using vinegar and steel wool. The plan was to use a friend's sand blaster but we couldn't get together and make it happen. I used wooden dowels to plug the bore and cylinders. The parkerizing solution came from Midway and was used on a couple of other pistols before this one. It's a fairly straight forward home ginsmithing procedure to parkerize smaller items like handguns.
You pretty much just heat the diluted solution to about 180° and suspend the bare steel parts in it until the reaction has stopped, usually 10-15 minutes or so. After removal the parts are rinsed with fresh water to remove any solution and them sprayed down with WD40. This removes the water and gives a nice oil coating for the new parkerized surface to soak up.
The results turned out pretty well. I didn't do any internals to avoid fitment problems and forgot to pull the thumb release out of the parts bag and refinish. I think it looks better than before and should be better protected from the elements as well.