You are correct, I am not sure about your numbers, but the fact is that an average bullet is fired at many many times the terminal velocity (maximum achievable speed from falling). It has no means to accelerate to any speed beyond its terminal velocity if it is accelerating only as a result of gravity. Mytbusters did a segment on just such an experiment. Not to say that Mythbusters are the supreme court of the physics world, but they did do this one. And because people who will argue this fact arent the sharpest tools in the shed, the best way to convince them they are wrong might just be with the talking box.
Mythbusters Episode 50, "Bullets Fired Up, Vodka Myths III"
Unofficial Mythbusters: Episode 50: Bullets Fired Up, Vodka Myths III
Given enough space, even a bullet fired straight down, will decelerate to its terminal velocity.