try some slugs.do you have the rifled slug barel?or the smoth bore.buy a couple boxes.dont go crazy.breneke ,lightfield,rem,winchester.all make a quality slug .everygun shoots differently even the same brand gun.get the ammo go to the range get it to hit the paper at 25 yrds.dont mater where just hit the paper.then you can adust your windage(side to side) and elevation(up down)once your hitting the center of the paper move out to 50 do the same thing.you should not have to go past 100 yrds .actually i would set it for 75 if the deer is further than 75 you can always hold high.Go get out to the range now and often you should have been doing this already.you owe it to the deer to shoot cleanly and accuratetly so you kill it quick.Good luck let me know how you make out
Now therefore take, I pray thee, thy weapons, thy quiver and thy bow, and go out to the field, and take me some venison.
Genesis 27:3 "The thinking deer hunter should mature through three phases during his hunting life. First phase, "I need to kill a deer." Second phase, I want to harvest a nice deer. And last phase, we must manage this resource so our children and their children can experience the grand tradition of good deer hunting." - Jim Slinsky