As you can see from the chart below, the cartridges have similar muzzle velocity, but the 308 carries significantly more energy from the start. Trajectory, too, is all but identical out to 400 yards.

Here's what you need to know about the 300 Win Mag vs the 308 Winchester. We compare them for ballistics, versatility, and accuracy. ... Shooters could opt for the flat trajectory of a 150-grain ...