1/2 cock is the 'proper' postion to cap the nipple, not full cock - In 1860's, Forsythe was asking that all 'rifles' allow capping at 1/2 cock to increase safety when capping. If cocking at full, then lowering the hammer to 1/2 bent postion, there is an opportunity for the hammer spur to slip and consequently discharge the piece.
Some locks today won't allow capping at 1/2 cock which is unfortunate, but many do. Harry, it is more dangerous to have to lower the hammer to 1/2 after capping. A low 1/2 cock postion is poor geometry.
TC got so many of the period correct aspects of a real Hawken wrong on their own rifle to suggest they knew or considered anything about allowing their customers to cap at 1/2 cock, the way they were supposed to. "Easy casting on a restricted size of internal parts" appears to be the reason the 1/2 cock notch sets the hammer so low at 1/2 bent.