How do you unlock the G18 pistol on army of two the 40th day?

Answer 1

To unlock all of the weapons you need to play through the campaign and make different combinations of co-op choices to get the weapons

EX; you can take the weapons from the storage locker and get the m416 but by making a negative choice you can't get the G18c from the doctor so you have to play through a couple of times to get them all

other weapons can be found in packages throughout the levels ATTENTION: at the end of the game, jonah has a bomb detonater, and he says that if u shoot him, the whole city blows us, its a fraud, he jus doesnt want u to shoot him, but do it anyways

Answer 2

Beat the game 2 times on contractor,beat the game 4 times on a lower difficulty,cheats called beatthegame,or you can customize a pistol of your choice 18 times different combonations 18 different times.

Answer 3

find them on the walls or from random box...