I know he had to do it so then Gunmu won't get caught by the rest of the members but shooting him is going too far 
My Top 5 Favorite Bl Manhwa
1 Passion
2 Codename Anastasia
4 Shutline
5 Payback
Bl:
https://mangabuddy.com/users/manga-list/152092
Action:
https://mangabudd