Whats the required inner barrel on the "Police Carbine" barrel. And I'm assuming that this Item is basically the same thing Minus the flash hider.
http://store.matrixbb.com/servlet/-strse-2...-CQB-AUG/Detail
While not planning as an extensive project as your's I'm planning on three barrel lengths ready to go. Standard, H-Bar and a one of the short Barreled designs.