this is my knex sub machine gun with removable magazine, extendable stock (my thanks to red book of westmarch) and red dot sight.

Step 1: Barrel

Step 2: Trigger

Step 3: Handle

Step 4: Magazine

Underneath the tape is green rods

Step 5: The Sight and Ram Rod

Step 6: The Stock

Step 7: Attaching Elastics

Add an elastic to the two the blue rod holding the yellow things in the last step and make this elastic go around the green rod on said yellow thing and attach it somewhere so that the green rod is being pulled towards the stock and upward. Attach an elastic. to the ram rod so that it goes forward and one to the trigger so that the trigger is pulled forward. Finally add one to the mag pusher so that it pushes the ammo up into the barrel.