Since the first instructable was near exeeding the size limit, here is part 2.
Step 1: Nose/Barrel (continued)
Very easy (in my opinion) to follow.
Step 2: Putting It Together
These pictures should give you some kind of an idea as to how it goes together.
Step 3: Adding Rubber Bands and Firing
I didnt include my crappy magazine because I know you, yes you, can make a better one (cough visper123 cough).