Kirk, remove the wood from the receiver. Have the receiver ultrasound cleaned and degreased,
then use printers ink to put a background to the engraving. The process is not complicated but I include a link to show the basic process.
https://youtu.be/USW4tJ-XZ2Q
Note: some people use Rustoleum in satin black color instead of ink. Same basic process, wipe on, then wipe the engraving with printer paper before the paint dries.