KG is great...Birdsong is the best, BUT you cannot do the Bird yourself, it is a proprietary polymer type coating that Birdsong must apply.
Depending on your cost factor, the best do it yourself stuff will be the Brownells baking type coatings followed by the Brownells air cure or Dura Coat offerings.
You will need to glass bead (Abrasive blast) your barrel and ensure all oil and other contaminates are removed.
If you have the coin, check into the Birdsong Coatings, I have many firearms done with this stuff, can't say enough good about it! The military machine uses this stuff also on 99% of their socom and other special unit firearms and items.
The Navy has had items submerged in excess of 7000 hours in salt water with no degradation of the finish or component!