How to make a paper gun that shoots pistol easy – Part 2

How to make a paper gun that shoots pistol easy – Part 2.
Part 1: https://www.youtube.com/watch?v=i1t0u9HW4sI
( P/S : You can see DEMO before posting your comment : https://www.youtube.com/watch?v=Lnto-qvAIuM )