ROB ALLEN TUNA RAIL SPEARGUNRob Allen Aluminium Tuna Railgun with Open or Low Profile Muzzle, 2x 16mm Rubbers and a 7,5 mm Spear. Rob Allen aluminium rail barrels have the same dimension as the carbon barrels. The rail level lines up with the profile of the mechanism and the muzzle. The integral rail is part of the barrel, thus increasing stiffness and reducing flex. This makes the guns deadly accurate. The rail barrel is manufactured from aircraft grade aluminium with a wall