This is my design of sentry gun. The sentry weapon system includes 6 barrel Gatling stile autocannon with ammunition storage and 3 multy purpose (AA=AG) missiles.
This sentry gun is design to be able to walk, change positions and then become stationary . The stationary position provides more protection as vital parts of leg joints are now covered with armor.
The design is not supposed to be real life physically correct, it's more like a stylised version of real life tech. I based it on my old sketch painted with black watercolor.