I hope that you enjoy this tutorial. These don't come often, because they just temporarily destroy my storage, so yeah.
Step 1: Handle
This is the fragile part of the gun, so be careful.
Step 2: The Rest of the Gun
Step 3: The Rest of the Gun Part 2
For all the side plates, you want 2 of every piece, but mirror the plates when you build them.
Step 4: The Rest of the Gun Part 3
Step 5: Enjoy!
And you're done! I hope you like your new Lego gun!
...that rhymed... ...huh...
Anyway, be sure to tape the handle to the rests of the gun, to make sure it doesn't fall apart.