This is my third K'nex assault rifle. The name comes from the fact that my brother james wanted a gun as well, so when I pounded him with my other gun, he could retaliate (Oh shit, Now James Can Kick My Ass Too!)

Interesting features:
10 round side-loading mag
Vertical pin blocker (for firing pin)
Sliding trigger

Step one has been completed, Feel free to comment on that. I make it with mlcad, but I havn't gotten the povray conversions to work, so if anyone else want to give is a whack, let me know.

http://knexinstructions.weebly.com/pump-action-p90.html
Has pretty good instruction videos, but he doesn't mention me on the site. The license I released the gun under require attribution, so yell at him to give me some credit or I'm going to have him shut down. :) (blogger and webs.com both respect DMCA takedown notices)

Step 1: The Hopper

The hopper of this gun is a solution to the problems I had with my 2nd gun. I jammed, BAD. Not often, but when it did, you needed to darn near take apart the whole front end to fix it. That and the fact it took un-godly amounts of time to load (20 rounds, drop in). With this system, ALL of the rounds are accessible at any time, and can be placed properly with much more ease. Both sides open, for both lefties, and righties, and both snap closed securely with no wonkey cut up pieces.

Some of the pictures are of a out-of-gun replica built for better visibility.

Step 2: Firing Pin Control

The control pin for the firing pin. This pin sits perpendicular to the firing pin and drops in front of it when the gun is cocked. When the trigger is pulled, it moves out of the way and allows the firing pin to pass.

Pictures taken with a out-of-gun replica.

Step 3: Sliding Trigger

Nothing really special here, but I don't believe anyone has used this design yet, so here it is. The trigger slides rather than pivots, which has a more solid feel. It is linked to the firing pin control pin through a few joints that can be seen in the main picture. Feels kinda like a Super Soaker trigger.

Picture taken on an out-of-gun replica, again

Step 4: Make the Side Walls

This gun's support is all in the side walls. You will need to make two, one for the left, and one for the right. They are identical, with the exception of one mirrored part (the red piece needs to be on the outer side of both. Just copy the pictures.