Winding it back for a second about the boat tails...
(lots of math incoming...)
It's important to understand that ballistic coefficient is
not a measure of accuracy.
BC is strictly a measure of the bullets ability to overcome resistance and negative acceleration.
This directly effects the distance a bullet will travel and the energy it will retain over distance, but not accuracy. Depending on the situation this can be critical to performance, can be one of several desirable factors, or can be largely irrelevant.
Metallic silhouette shooting is an example where BC can be critical. In metallic silhouette you need X amount of energy to knock over a target at 500m.
Say you have these two loads...
1) 150gr bullet - 2900 fps muzzle velocity - .300 BC
2) 150gr bullet - 2900 fps muzzle velocity - .350 BC
As the bullets are in flight they're slowing down and losing energy at different rates.
At 500 metres the .300 BC bullet is moving at 1,550 fps and carrying 800 ft-lbs energy.
At 500 metres the .350 BC bullet is moving at 1,710 fps and carrying 970 ft-lbs of energy.
Say you need 950 ft-lbs to knock over your silhouette at 500m, this is impossible with the .300 BC bullet. It simply can't retain enough energy to knock the target over. In this instance the higher BC (more specifically, the additional energy it retains) is critical as you can't knock over the target without it.
I'll come back to this in a second but the .300 BC load has 17% less energy and 9% less velocity at 500m than the .350 BC load.
At 100m it's a different story.
At 100m the .300 BC bullet is moving at 2,600 fps and carrying 2,250 ft-lbs energy.
At 100m the .350 BC bullet is moving at 2,640 fps and carrying 2,320 ft-lbs energy.
At 100m the .300 BC bullet only has 3% less energy and .5 % less velocity.
For the purposes of hunting, this reduction in energy and velocity at 100m is completely insignificant. Things like initial penetration, bullet expansion, weight retention etc. all become the critical factors. Enter the Barnes TSX...
You mentioned where the balance lies in this...
Where BC does influence accuracy, but not directly correlate with it like it does for velocity and energy retention is flight time.
Because a higher BC bullet moves faster and is in the air for less time, there is less time for it to be effected by wind and other outside influences.
At 1,500 metres the .300 BC bullet above would have a flight time of about 3.8 seconds.
At 1,500 metres the same load with a .500 BC would have a flight time of about 2.8 seconds.
1 second less to be affected by wind, up-drafts etc.
As you move towards that end of the scale that's when BC itself because more desirable, if not critical.
Then, if you shot the above .300 and .500 BC loads in a weatherless vacuum, BC would become irrelevant again
(make sense?
)
need all the help I can get 
