The truth is, groups are mostly useless for hunting rifles. They do work to a degree, because they speak to a rifle's consistency. The problem comes in the fact that we don't often shoot 2 or more shots at the same spot when hunting. As I understand it, in Germany, rifles were tested in terms of where the first shot from a cold barrel went, and that would determine whether it was pulled from the line and sent to the snipers. The ultimately impractical true test would be to fire the rifle once at the target, come back the next day and the next, doing the same thing. Were all three days' first and only shots in the same place? If yes, you have a truly worthy hunting arm. I cannot remember the last time I took a second shot at a deer (actually, I do remember borrowing a rifle, and shooting 5 rounds at a buck, as he calmly watched, and then trotted lazily off as I stood dumbfounded, deaf, and disgusted). The good of groups is only that we can hopefully track to some degree the extreme spread of highest/lowest, leftmost/rightmost shots. To the OP, we know certain things that will tend to wreck good accuracy, such as poor bedding, stock flex, stock contact points, poor rifling finish, inaccurate chamber reaming, etc., but there is still a lot of witchery involved. A lot of this may be due to barrel harmonics, and some manufacturers just get it right, it seems. The things that tend to contribute to good accuracy are well known now, so most all manufacturers adhere to them, and overall rifle accuracy seems to be on the rise compared to 100 years ago or so. Add to all this the question of where one draws the line between hunting and live-game target shooting . . . one should always conduct one's game shots to their sphere of comfort between rifle/ammo/accuracy/energy/bullet construction/game position/game size/game construction/shooting position/weather conditions/lighting . . . you get the picture.
I heartily concur. 
