To be honest, I'm a little unhappy about drilling into my stock. Not because I lack the skill, but because the for end swivel will be where I sometimes want to put my hand. The stock I have has the rose wood end added on. I don't trust the glue joint to hold 100% while the stock is under pressure from the sling. But where the rose wood is, is where the swivel should be.
I'm not going to do anything about a sling just yet and see how it goes for now.