Is there any problem with cold rust bluing an entire FN bolt and extractor? I'll be using the Swiss Armoury formula.



I'm thinking of any effect the bluing may have on the lugs, etc.

I'm not familiar with the Swiss Army Formula. In the rust bluing I've done the one thing that you might watch for is not having too polished a surface. Rust bluing needs a little something to grab to. You might finish to about 320 grit but not over 400........DJ

The rust bluing itself will not harm the bolt or extractor.

Good advise from djpaintles. I polish everything to about 600 grit, but then give a quick micro blast with 320 grit silicon carbide at 20 psi. You really can't even see the effect of the sand blast, but it gives enough of an etch to let the rust get a good and even bite. It's the "even" part of that statement that is important.