There is one way to repair that chip without it being all that
noticeable.
1. At the very top of the stock, right above the chip, you saw a thin,
as possible, cut about an inch long. Use a thin blade; I've improvised
a hacksaw blade by grinding it thinner and sharpening the teeth with a small file.
2. Cut straight down behind the chip, and just a shade deeper.
3. The repair piece you get from removing the buttplate and scarfing a
sliver of walnut out of the buttstock. Drill two hole and chisel the piece out between the holes.
4. Sand the scarfed out piece into a thin wedge; much to the shape of thoses wedges you get with a new hammer handle.
5. Once you've got it to size; apply some epoxy glue and drive the wedge
into the cut you made in the stock. Tap it down until it reaches the depth
of the chip.
6. This will bulge out the wood where the chip is, creating a bump. When the glue has cured, sand the bump away and your chip is gone.
7. If you think the wood is too dry to expand; sand some of the finish off and
rub on lots of hobby grade linseed oil. Let it soak in for a few days, putting
on more as it soaks in. This will help the wood to swell out without cracking.
8. Refinish as necessary.
I've done this repair a few times and it worked pretty good for me.