Battle, I stain after filling and before top coating .

A solvent based dye type of stain like TL stain or Behlens Solar-Lux. As apposed to an oil based pigment stain like Minwax or a lot of the hardware store stuff.

I didn't invent this method. Lots of custom stock makers and gun makers use it.

As with most stuff in gunsmithing there are lots of ways to do things. If you get results that you are happy with thats what is important