You had to pick a Flusie for this question, didn't you. Some bad results can sometimes occur when a gun is re-cased. Frame warpage primarily, and the 20ga Flues model is known for (some of'em)having a frame likely to break.

I'd leave it gray or silver or whatever it is now, or just get it blued if you have to do something. Just my opinion, for what its worth...Geo