Papadragon

Hi there, I'm kinda new to this game. I finally got a weapon (Mosin 1930) and my friend decided to bring a few adventurers into my ambush at a village. I was standing near an opened window on a second floor with a view on the water pump. I leaned (e) and aim/zoom at the head with spacebar up but not with the iron sight vision (weapon's vision). The shot hit the wall instead on the left in the house. Do we actually need to be in a weapon sight to shoot? or being in a 3rd person perspective is enough. Do we need to be crouch? I fired a shot in 3rd person view before to make sure and it was accurate... and it was. Does leaning is the issue? Is it the breaking window? Thank you! Sorry about my english!