I guess BC might be important out beyond 300, but inside? What difference does it make?
It makes a measurable difference.
For scientific purposes I will use the same weight bullet and MV with an imaginary BC, for each.
Lets just say we're firing a 70grain .224 diameter bullet @ 3000fps.
@100 yards a bullet with a G1 BC of .2 will have slowed to 2523fps, from 3000fps. This yields about 989ft/lbs of energy with about 2 inches of wind drift in a 10mph crosswind, with 2.39 inches of drop from the muzzle. Temperature 65 degrees F, at sea level.
Keeping EVERYTHING else the same and giving the bullet an imaginary BC of .65
@100 yards the bullet has slowed to about 2849fps yielding 1262ft/lbs of energy. With only .88 inches of wind drift and 2.21 inches of drop.
Increase the range to 200 yards and the difference grows even further.
BC .2 = 2107fps, 690ft/lbs 10.31'' drop 7.14'' drift
BC .65 = 2707fps, 1139ft/lbs 8.73'' drop. 2.25'' drift