I've shot enough bears that I've lost count and have seen a lot of others shot using archery gear all the way up to 33 Nosler and 45-70. In my experience middle of the middle is starting to get a little too far back and on the shoulder like an ungulate such as deer is too far forward. The vitals are set back a little further on a bear compared to ungulates. My preferred shot on a bear that is broadside is half way between the top of the back and the bottom of the brisket, this accounts for the several inches of hair hanging from the brisket, then 4 inches (or the width of your hand) back off the crease of the should if the near side leg is straight. For all non-broadside shots you need to think of a bear, much like any other animal three dimensionally since they aren't flat and envision where the vitals are based on what I described above taking into account the angle of the animal and the position of it's near side leg to make sure bones aren't in the way. Leg bones obviously aren't an issue for midsized and up cartridges when using premium bullets. The last bear I shot was like 6'7" or 6'8" and was a very hard quartering away shot with a 6.5 Creedmoor at like ~75 yards if memory serves me right.. The bullet (124gr HH) did it's job as designed, the base passed through a few feet of bear and exited causing the bear to drop at the shot without hitting the spine. Not saying they will always drop at the shot with this shot placement but they never make it far regardless if using an arrow, little bullet, big bullet, slow bullet, fast bullet. Another benefit to staying off the shoulder besides potentially losing a bear (learned that lesson the hard way and have seen others do the same), is reducing the amount of damaged meat as bears make damn good groceries, especially sausage.