In the F3 official game guide it suggests you try sniping at Allistair Tenpenny from the ruined office building, which is quite an uphill shot.
I have tried numerous times to snipe him from there, with the Sniper rifle and also with the Gauss rifle. And from atop a couple of rocks in the area.
All I seem to be doing is chipping little bits off Tenpenny Tower. I really can't even see him.

Has anyone succeeded in sniping him? From the office building or anywhere else on the ground?