The 870 Express Youth model comes with a 21" vent rib barrel with RemChokes and a 13" LOP stock- that's a near ideal out of the box multipurpose gun, for a lot of smaller statured shooters. You should be able to buy that same barrel from Remington, or one of the places like Corson's or Barrel Exchange.
There used to be a Junior version too, with an 18.5" VR barrel and a 12" LOP stock, if I remember those dimensions properly. Don't know if they still make it.
And Remington makes the HD version of the express in 20 gauge too, with a magazine extension and a plain 18.5" barrel. Again, that barrel should be available from Remington. See
http://www.remington.com/products/fi...c-7-round.aspx .
Give Remington a call during business hours (in NC) at 1-800-243-9700 and ask the parts people...
lpl