Quote Originally Posted by vbull View Post
The case coloured Webley I saw I believe was done properly with bone ash etc. I bought an old Marlin from the same guy which has had the treatment, looks great but costs a lot due to the ingredients used so I don't think he would cheat on the Webley. I'll ask him though. Here's a couple of pictures.

https://flic.kr/p/22rseid
https://flic.kr/p/23tnWd7
This gun Smith has a good gallery of example images. They clearly work on any type of gun, but I see why it might be a difficult task to do on the thinner metals of an airgun vs the more robust sections of a firearm.
http://www.gunrestoration.co.uk