A hard cast bullet will kill the deer, but you may have to track in across 3 counties while it bleeds out. Use a Hornady XTP bullet if you want the deer to fall where you hit it.
From Gun Test mag.:
"Among the commercially available bullets in these grain weights, we would pick Hornady XTP bullets for hunting deer-size game. In our field experience, the XTPs have proven to be accurate, tough, and deadly. Also, factory loads with the XTP in .44 Magnum are available from Hornady and Black Hills Ammunition in both the 240- and 300-grain weights. Top-performing handloads use 24 grains of Winchester 296 powder and a CCI magnum primer for the 240-grain XTP bullet and 20 grains of 296 with the 300-grain bullet. In our guns, these loads give us about 1,400 fps and 1,200 fps respectively, depending on barrel length. "