Go near the secondary objective doors you can find in trainyard, and underground, face the wall and make the turret spawn on the other side ! Really easy to reproduce and exploit.
So you can make turret spawn inside the 1rst obj of underground when diffusing for example, same when the door is closed on trainyard …
This also used to work for mines. you places them on side 1 of the door, but they exploded on side 2. I don’t know if that is still possible though, because I don’t play proxy anymore. It was really usefull at previous underground, because attacker needed to plant c4 at the door and they would always trip on an invisible mine (placed on the other side of the door) <3 free kills.
This also applies to ammo crates.
Bridge ammo crate at the 1st obj at the bottom of the stairs on the right, can be accessed through the wall on the other side.
Please don’t brag about it, turrets are already very annoying, without people glitching them through walls.