Do you know if the action has been annealed to make it softer for engraving ?
So I am asking; How hard is it now ?
Test it with a file or a graver & see if they bite into the soft metal or glide over something a lot harder.
You must establish what you are starting with before doing anything.
Did the local competent gunsmith test for hardness & say that the action has been annealed ?
O.M