Metal Gears solid 4?

Question

What non lethal weapon(exept the solar gun) could i use to kill the 4 boss (human form) in metal gear solid 4 because i want to get their face in face camo of old snake.

Answer 1

A tranq gun so they pass out by a loss of stamina.

Answer 2

Tranquilizer gun is best for that and Mosi Nagant.

I rarely used Solar Gun - it's easier to headshot with Tranq gun.