If you do it right then it will come out great. If you half as3 the steps it will come out bad.
Degrease it
Abrasive blast it
Degrease it.......It can not be too clean
Parkerize it
Clean it......the scaling
Dry it, heat it up
spray it, let it sit for a half hr then bake. (hope you have spraying skills)
If you don`t want to do all of that send her to me and I will give it a nice coat, I have restored some nasty used stuff and made them come out perfect. I have a ton of experience with the Sig series pistols.