You could always brown it with Mark Lee Express Brown #2, available from Brownells dot com.
After browning it, chuck it into a pot of boiling water. It will turn black as the ace of spades.
Dry, oil, reassemble, shoot.
Or, you can make your own hot bluing salts. All you need are Lye, ammonium, postassium, or sodium nitrate, distilled water, a steel pot, and a turkey fryer or Coleman stove.
www.homegunsmith.com
Go to the gun and stock finishes section. The sticky at the top is "Hot blue my way, step by step".
It's all about homemade hot bluing.
Sure wish I could get it black nitrided, like the slide on my Ruger SR9.
Being a native Georgian, your 15-5 reminds me of my 10-6. I bought it from the LGS who bought it from the Columbus GA Narc Squad. It was a seizure gun. It sat in an evidence locker for God knows how long and acquired a rather uneven tan.
I removed the rust with oil soaked brass brushes and oil soaked 0000 steel wool, combined with a generous helping of elbow grease.
Now, it's blue and white. I'm undecided about refinishing. I'd love to send it to Smith to have it look new again.
I don't like gray Park on a revolver. I guess I could park it and then dunk it into used diesel motor oil.
Or, I could get it black Parked. I think that's correctly referred to as Bonderizing.
I could also bead blast it and hot blue/black it at home.
I just don't feel right having a non stainless or non nickel S&W revolver that's not shiny blue.
But, I got it cheap. It's not like I'm hurting the value.
Maybe I could blast it and brown/black it with Express Brown.
For now, I'll just use Oxpho Blue (I use the creme) the white areas.
You could always clean it up and oil it and keep it "in the white".
Yeah, me neither.