Pump Action P-90 By the knex gun boy in LivingLEGO & K'NEX1,0454Save PDFFavoriteIntroduction: Pump Action P-90By the knex gun boyFollowMore by the author: This is my first pump action knex gun ive ever made Step 1: The Pump The pump is realy comfertabel. It works just like a nerf gun.Wich gun i shoot next time?