Recently, I received the Widowmaker, and thought that initially it was a very useless weapon. It required metal to shoot, and did the same damage as a normal shotgun.
However, on one server I played on, something weird occurred.
My setup was: Widowmaker – Pistol – Gunslinger
I set up my mini-sentry, and when I switched to my Widowmaker, the minisentry targeted an enemy and began to shoot him. And I immediately began to receive metal. I received metal until around 412 metal (which was odd, because the cap was 200) and then my mini-sentry was destroyed.
I tried the exact same scenario on a different server, and it didn’t work. So since I tried both, I’m extremely confused whether or not having a sentry shooting at an enemy while in the primary slot (Widowmaker) grants you metal?