The Hostile Sentry is an Epic Robotic Turret in Unturned 3. It must be powered with a Portable Generator or Industrial Generator, and placing a ranged weapon inside of it will cause it to shoot anything hostile in the area.
Range and fire rate is affected when using a Hostile Sentry, and Magazine Attachments must be replaced when emptied, or it will stop shooting.
The calculation to decide range is Math.min(48, <ranged weapon's range>). Fire rate is roughly 2.5 to 3 times worse.