If a gun is sighted in at 100 yards and you aim at a target closer than 100 yards the bullet will hit high. Beyond 100 yards it will hit low. That's just the practical implication of living in a universe with gravity.
A .223 has a muzzle velocity around 3300 fps. That provides a very flat trajectory. It shoots "like a frozen rope" out to 150 to 200 yards. That why gopher hunters love it.
The gun guys are gonna get you on this one. I don't know of a single (decent) high-powered round that doesn't rise before it starts to drop. The bullet is traveling that fast through AIR, so yes, aerodynamics are involved.