Final answer:
The elevation knob on the M16A2 Rifle adjusts the point of aim by changing the angle at which the barrel is tilted. It can be adjusted in minutes of angle (MOA) or clicks, with each click typically corresponding to a change of 1/4 MOA.
Step-by-step explanation:
The elevation knob on the M16A2 Rifle adjusts the point of aim by changing the angle at which the barrel is tilted. This allows the shooter to compensate for the effect of gravity over different distances. The adjustment can be made in minutes of angle (MOA) or in clicks, with each click typically corresponding to a change of 1/4 MOA. So, depending on the specific rifle and sight setup, the elevation knob can adjust the point of aim by varying amounts.