You can have the best equipment, best rangefinder, best ballistics software, best ammo and if your comfort zone to hit a 12inch target is at 600 yards (8 rounds hit from 10 rounds shots) THAT IS YOUR MAX DISTANCE ON DEER SIZE GAME.
Shooting at 100 yards at the game involves more then just upgrade your rifle and your rangefinder.
You have to go out with your equipment ant take FIRST ROUND COLD BORE SHOT at 1000 yards, 800, 600 etc.
record all your shots and try to improve by shooting more (cold bore shots at 12in target)
try of bipod, up hill down hill, of backpack (sometimes you have to much snow or grass and is no way to be prone) and you have to use shooting sticks or improvised.
ALL YOUR SHOTING HAVE TO BE 1ST ROUND (Cold Bore Shoot)
keep in mind when you go hunting and your dream game shows up your 12inch group is opening up due to (buck fever, rushing the shot, improper shooting position, etc)
In Hunting you don;t have sight in shots or fowling shots.