The original design is from Wootgineer...think that's the name. I sort of revised his knex handgun to see what I could do. It still has the magazine but now not only with the slide action it also has a pull back ram rod attached to it as well. Unfortunately I have not tested to see if it actually fires but I think it might. Looks realistic,. feels comfy and feels like a real gun well to me it does. If you want instructions to this then ask but I made two of these and I'll post the whole photo montage up with this one because I originally made a set going with the handgun/pistol.