A sentry gun is a tactical weapon used in wars. The sentry gun has 3 prior knowladges to it. First is never leave the sentry by itself you never know if anyone is going to destroy it with a knife. Second prior knowladge is dont fight back as mutch just sit back relax and let your weapon do the job. Last but not least dont put it right infront of the enemy whoever does that is a dumbass lol xd. Sentries are used all over the world its a very powerfuls weapon used by militaries. Cya!