p5200, that 117 grain GK bullet at 2900 FPS muzzle velocity will get to 280 yards within 3" above or below your point of aim and still have 1350 foot pounds of energy so it will certainly kill deer easily at that range. I would note that it will have almost 7" drift of windage at that distance if you have a 10 MPH crosswind.
A look at Hodgdon's website will get you load info.
Lance