So I have a friend who wants to barter a Remington Model 11 20ga shotgun to me in trade for some auto parts. I have a blue book of gun values that is relatively recent. The big rub on this gun is that it was his moms, and when it was still relatively new, they shortened the stock to make it a "youth/ladies" shotty. How much should one knock off the value for that? I know a refinish usually knocks about 50% off the gun, but not sure how much these mods kill the value.