Here is my knex gun. I made it after getting bored with seeing the same old killerk ripoffs over and over again. It is single shot with a sear-system trigger. If you use the right bands, you can get it to go about 30ft.
This is my first Instructable, comments are welcome. Here's me on Youtube firing it.

Step 1: 1

Ok, you lasted this long on another knex gun Instructable. I suggest you pat yourself on the back and have a soda/beer.
Anyway, the first thing you need to do is make all the pieces/parts.
Pics are going to do a better job of explaining. Here is an exploded view of the gun.

Step 2: 2

Ok now you've seen the all the parts and seen in the video how they work. I'll show how to build the individual parts now, starting with the barrel.

The barrel is made of 2 grey rods, 17 red pieces (45 degrees), 3 white pieces (full circle), 2 yellow pieces (half circle), 3 blue pieces (full circles that slide together), and 2 green pieces (tiny rods). The tactical mount is made of a yellow rod and 2 blue pieces. Assemble as shown in the photos. Didn't get all of that? Reread this paragraph and look at the pics. Still didn't understand what to do? Advance to nearest large drop and jump over. You're a waste of oxygen and contribute nothing to the human genome.

Step 3: 3

Alright, assuming you're not a revenging corpse or ghost, we'll work on the handle. Oh by the way, I was just kidding about committing suicide. There is a rubber band on the handle to desensitize the trigger. It's right on the green piece in the middle.

Step 4: 4

Right, now we'll make the trigger. It is designed to release the cocked plunger by pushing on it.

Step 5: 5

Ok now for the plunger. It is a good idea to put some tape where the yellow piece and red rod connect. I found that multiple stretchy rubber bands work better than one heavy band.

Step 6: 6

Now for the trigger block/ rear assembly.

Step 7: 7

Now to assemmbly. The trickiest part is the rear/trigger assembly. You can see that the blue rod on the trigger slides into the holes on the green pieces of the block. A blue spacer on either side keeps them stable.

Step 8: 8

To commplete the rear assembly, you need to connect the trigger block and handle. The trigger is to slide into the center of the handle, and be held by the rubberband.

Step 9: 9

Right, putting it all together. The handle snaps onto the barrel and the plunger slides in, and is secured by the rubberbands, which loop onto the yellow pieces. You can change their position to compensate for rubberband size.

Step 10: 10

All of those white pieces are ammmo clips. I find for maximum effectiveness, shoot either 1 blue rod, 2 white rods, or 5 green pegs. To cock, pull the plunger back and set it on the trigger block (as in video). Pull on the trigger, point the barrel and fire. Oops, my bad, point your barrel before pulling the trigger (duh). I can get about 30 ft with the blue rod, and about 15 with the green pegs. The tactical mount is perfect for a small flashlight and red dot projector.