The necessities for the gun are not only very high power ( any big gun could do that ) , but that it can be carried for long periods , shot from any position , and be well balanced enough to track on rapidly moving animals . The necessities for the gun are not only extreme power , since in that case the 50BMG or 20 mm cannons would be the order of the day , but that it can be carried for long periods , shot from any position or angle , and be well balanced enough to track on rapidly moving animals .