im not gonna explain how to made it, but it is very easy to made, just take a good look.
I also made a few photo's of the difficult parts, so enjoy!
Step 1: Take a Good Look
here are the other parts
Step 2: The Trigger
the trigger is very important,
it looks a bit like killerk's gun
but it is different!
as you see you have to modifie 1 piece
just cut it off.
Step 3: Fire Part
this is the most important.