You should be able to get a Mossberg "youth" stock (12-13" LOP) that will fit a 20 ga. with no problems -- either from Mossberg, or used, from someone whose kid is getting bigger and needs a full-sized one. The wooden stocks are inexpensive. Mossberg also makes shim kits that let you adjust both the LOP and the angle of the stock and receiver -- a custom-ish fit, for not much money, with a traditional-looking stock. The AR-15 style stocks aren't ideal for a shotgun, especially for a new shooter. They tend to bite the cheek, which is discouraging for a beginner: it's not supposed to hurt...
Call Mossberg (800-363-3555)and ask them what they have. I think you can get a new one for $60-ish; less if you can find someone who's moving to a longer stock and wants to sell a used smaller one.
"Once the writer in every individual comes to life (and that time is not far off), we are in for an age of universal deafness and lack of understanding."
(Milan Kundera, Book of Laughter and Forgetting, 1980)
Last edited by Vanya; February 14, 2013 at 10:16 PM.