hey slacker, i work in a furniture store and have had some experience w/ dented, gouged, and even totally blown out wood. if i were you i would find your nearest furniture repair store and ask for a wood repair crayon (matching the color to your wood, of course). its a hard waxy crayon that once dry and if applied right will stay forever, and if matched correctly you wont see it unless you know its there.
heres how to apply:
use a lighter, melt it just overflowing into your gouge, use a credit card to flaten and slightly spread the wax blending it w/ your grain, once youve done that youll only see it because its matte instead of gloss, soooo-just use a gloss spray overcoat (like spray paint) and your gun can look as good as new.
thats if your gun stock is worth $10.00'ish and 0.5 hours plus driving of your time. i hope that helped. sean