Actually you want a rifle to hand down through the ages, get a T/C Hawkins. They are not new technology, but history has shown that the style of rifle and their tuff nature will have them outlasting many other rifles out there. Also with their old world charm and beauty, they are something to hand down to special people.
It's not an in-line, but
BINGO! That's the kind of rifle to start a family heirloom tradition. Take off the buttplate, drill a hole in the stock and put a paper in there saying when you got it and what you know about it (age, price, etc.).Add a note that each new owner should add to the note saying when they got it from the previous owner and who they want to pass it along to. Make sure everyone in the family knows that note is in there.