Custom made by me from a functioning AR-7 pistol, this piece requires shipping to an FFL, as it is considered a live firearm.  Grip is from an original Sterling L2A3.  To modify the grip, I created a "tang" from the original grip, and secured it permanently.  Scope is a real aim point, but not the exact one used in the film (you can switch out for an original, more expensive "correct" one, or buy a reproduction from www.blasterfactory.com.  Mortar Fin is an original "found part" - I had the barrel of this pistol shortened and tapped with threading, so the fin-assembly screws on.  VERY solid construction, best available prop on the market.