My son who has been hunting and shooting with me for some time, is at that point where he's in between a youth gun and a adult size stock. I'm looking for a 28'' 20 gauge barrel to replace the 24'' he currently has on his 391. Does anyone know where to get one( that's not the price of a new gun) or have one they want to get rid of. I do not want to get rid of the gun because it will be the right size for his 10 year old sister to use once he gets a 12 gauge. Thank you in advanced.