I have a long barreled Luger project waiting for machine time right now...I had a thread up about it, but I think I may have deleted it...Here's two pics from it [below]...
The amusing part is that without extensive lightening, the barrel won't recoil...The gripframe will fore-coil...
You'd have to hold revshop's 20" barreled action/pistol in two hands to shoot...And instead of your front hand going back, your pistol-gripping hand will travel forward...
I think that is hilarious...