BC (Ballistic Coefficient?)

[natman]

Imho bc=bs

Then I'm afraid you are misinformed. BC is a major factor in how bullets behave downrange.

f you shoot at ranges over 150 yards it's a big deal. Let's compare two Federal 150 grain 270 loads, one a roundnose and one a boattail spitzer:

Load Caliber Muz 100 200 300 400 500
270B 270 Win. 2667 2057 1563 1166 859 629
270C 270 Win. 2667 2320 2010 1733 1487 1268

At 300 yards the boat tail has almost half again (49%) more energy. In order to get the same energy at 300 yards with the RN, you would have to start it @ 3245 fps from a 270 Weatherby Magnum, with an increase in recoil, noise and cost and a decrease in barrel life.

Or you could make the change to the boat tail and get magnum performance with no extra recoil, noise or cost.

The US government figured this out 105 years ago when they switched from a RN in the 30-03 and reconfigured it to shoot spitzers as the 30-06.

So it's not BS.

 

[natman]

To answer the OP's question, BC stands for Ballistic Coefficient, which is a number that indicates how well a bullet will penetrate the air. Bullets with a high BC lose velocity due to air resistance more slowly than bullets with a lower BC. This means that they shoot flatter and reach the target faster, which means they are less affected by wind.

Here's a comparison of the 150 grain 270 loads. The only difference between these two loads is the BC of the bullets: