A good leader does not routinely operate at anywhere near his physical, emotional or intellectual capacity. The good leader is always pacing his efforts so that he has enough reserve to sustain his concentration as long as necessary when unexpected events require.
A person operating near 100% capacity is a person operating at the edge of his envelope of reliability.
That person will not have the ability to take a bullet - of any caliber.
No individual is so good or so indispensable that he is immune to professional trauma. It's all in the leadership game. Susceptibility to taking a bullet is one of the downsides of the game. The ability to recover from adversity is an ability a leader must have.
From RADM Dave Oliver's great book LEAD ON!