Re: how can i make my gun more accurate
The real answer is to learn to shoot better. Clearly you have not put in sufficient practice to make shots of that distance. The best thing that you could do is to shoot your rifle from a supported position at various ranges so that you will know where it will hit at each distance. Then practice doing the same from field positions. A BDC scope can help with hold overs but it will not reduce the need to do the hard work. Figure out what kind of field position you shoot from most of the time (including any rest you typically use) and see how far you can shoot 3 shots, including your first one, in a 6" circle. That will tell you how far you should be taking a shot at game.
PS I chose some arbitrary numbers, but if you can put your first shot in a 6" circle, you should be able to hit the vital area of a deer at that distance.