KTP is a dual barrel knex pistol, that has 3 firing modes:
Semi auto (Strong)
Dual shot (Stronger)
or Single shot (Strongest)

I built it as a sidearm, and it works great.
You can easily turn it into a rifle,
but I didn't have enough knex to add a longer barrel or a stock.

The single shot can put a quarter inch dent in drywall!
It help if you tape the ammo though....

Its semi auto mode isn't quite true semi auto, but it fires at the same rate as one.
You see, it has two triggers, side by side...

Let's get building!

^{and credit to DJ Radio for the inspiration}

(Single and dual shot mode shown in pics)

Step 1: Barrel Part One

This is the back end of the barrel.

1. Build four of these.

2. Clip them onto a yellow rod.

3. Build this.

4. Put them together here.

5.What you should have

The yellow rod might slide out, but just keep it there for now.

Step 2: Barrel Part Two

This is the front end of the barrel.

1. Build these. The color of the pieces doesn't matter.....

2/3/4: Connect them onto a yellow rod then clip a blue rod on the other end.

Step 3: Completing the Barrel

You now need to connect the two together!

1. Clip the yellow rod and onto the snowflakes, and a blue rod onto the yellows.

2. Build ten of these.....

3/4 .Clip them on like so... 3 on one side, 2 on the other.

5. Do the same here.....

Now put this aside, and lets work on the handle!

Step 4: The Layers

The gun consists of several layers.

1. Build/get all of these.

2/3.Put them in this order

4. Clip them together here.

Step 5: The Handle and Triggers

1. Put one of the little white rods with a tan lock on it in with the two snowflakes. The white rod will hold them in place.

2. Add a blue rod to hold it together.

3. Add a tan lock and white rod in with the triggers....

4. What you should have after you add another blue rod.

Step 6: Connect the Barrel to the Handle

1. This will be easier if you take the white rods out. Slide a blue rod through the greys, then add a yellow connector.

2-5. Clip the blue rod onto the other yellow connectors, and the other blue rods onto the snowflakes.

6. Put the green rods back in.

Step 7: Trigger

This is the trigger.
Pretty simple:
Get two gray connectors, put y connector on each one,
the clip them onto a blue rod. Thread a long elastic through them....
Clip it onto the two triggers.

Step 8: Loading and Firing.

This is what you need to do to fire it:
For single shot or dual shot, you need:
Rubberbands
Either one rod with an orange connector on the end,
or two L ammos.

Put the rubber bands on like so,
then put the ammo in as shown.

If you want to fire in semi auto mode, you need to do a few more things:
Take the blue rod and grays off the triggers.
Put white rods on.
Put the blue rod behind the whites.

Then load the ammo and put the elastics on like shown.

Oh, and here are some pics of my rifle, that uses the same system. It's just bigger......