The Longclick length is 105mm (4,134"). I do shorten (with a carbide pen mill) this barrel's pen after finishing mainly for converting the Long click ballpoint pen to a mechanical pencil, using a Schmidt DSM 2007 mechanism. The minimum shortening is 1,5 to 2 mm (0.06 to 0.08") but 3mm (0,118") works fine for the DSM 2007. One can also use this shortened barrel as a ballpoint pen but I generally avoid if it's shortened more than 0.06" for the Parker refill extends too far and, while workable, it's unsightly.
Hope this helps.