Operation Gear Grinder
Operation Gear Grinder is an expert-leveled Mann Up mission added in the October 9, 2012 Patch. Much like Operation Steel Trap,Operation Gear Grinder is a Mann vs. Machine Tour of Duty in which players stop a horde of robots from delivering a bomb into the bomb hatch near the respawn. Completing a mission will destroy a Tour of Duty Ticket and award loot. Completing all three missions in Operation Gear Grinder will result in special Botkiller Weapons. However, instead of Gold and Silver Botkiller Weapons, Carbonado and Diamond Botkiller Weapons are rewarded upon completion of the tour. Carbonado robot heads are black robot heads, while Diamond robot heads are a highly reflective like Robot head. These weapons are variants of the Stock weapons and always come in Strange quality.