It is a though little K'nex gun that I made. It can shoot a white K'nex rod 8.5 feet (2.57 meters).It isn't great because I am new to instructables but it is worth making and is quite simple so it only takes a few muinets to build. Sorry about the bad images.
Step 1: Barrel
put an oarnge connector on each red rod then attach the rods and keep adding the connectors till you have used 22 and it looks like the last image.
Step 2: Spacing Barrel
Take 28 blue spacers and put half on 1 red rod and put the other half on a red rod next to the first. Then take a blue rod and 2 yellow connectors and put them together like in the 6th part of this step. then add what you just made to the barrel as shown in picture 7.
Step 3: Slide
Take 4 grey rods and 4 blue and then 1 white connector and put all the rods on to the white connector alternating blue to grey like in picture 5.
Step 4: Putting It Togethor
Take the slide and put it into the barrel as shown, make sure you get all the grey rods into the oarnge holes.
Step 5: Rubber Bands
Take the rubber bands and slide them on to the blue rod as shown in step 3 then re fasten the yellow connector stretch the rubber bands
to the slide, you may need a different type of rubber band or to swap they grey rods in the slide for red or yellow ones.
Step 6: Fireing
Pull back the slid you should get resistance from the rubber bands. place the ammo (1 white rod ) in the barrel oppisite the rubber bands
keep the slide back aim away from face then let go of the slide. When the gun fires the blue rods in the slide move, move them back before fireing again.