options
There are several options. It depends on the amount of cash one is willing to spend and the quality of finish desired. It would be cheap to reblue it at home, but it would require a little work and it would still just be blued, and bluing is really just pretty rust anyway. It looks great when done right, bad if rushed.
OXPHO-BLUE® CREME at Brownells
Next would be a spray on finish that works cold. Aluma-hide from Brownells is one. It's paint and it will wear. It also builds up so it's not for parts where tolerences are important.
ALUMA-HYDE® II at Brownells
Next, bake on paint. Same tolerences, more durable.
AEROSOL BAKING LACQUER at Brownells
Or Duracote. Popular and easy to do.
DURACOAT PAINTING SYSTEM at Brownells
Now me, I would get it professionally refinished. I can't help but think of paint finishes as temporary. I'd rather pay more, once, to do it right and have it passed down to my kid in good shape. I use this place, there are lots of good places just like it.
Gun # 28
The rollmarks on the Walthers are not deep, and careless polish work will leave light marks and washed out areas. Notice the marks in the picture are still sharp and deep, a sign it was done right.
Customer Photos
The disadvantage is that it costs a lot. Sometimes more than the gun is worth, sometimes not.
And there are plenty of good refinishers, I don't want to endorse one in particular, so...
Robar NP3 Firearms Finish
Gun Refinishing, Plating, Jewelling, and Polishing. Wildwood, Florida