Ever wonder how exactly a sentry gun works, and what the many options actually do? Well, this is for all you die-hard TF2 fans. I found this great PDF with lots of great material on the Engineer and his Sentry Gun! Click the image to view the manual.

Senty Manual

This was found at the following link: http://www.steampowered.com/v/index.php?area=game&AppId=440&cc=US