The initial speed of a gun can affect bullet velocity, particularly when considering factors like shooting from a moving vehicle or lurching the hand forward while firing. However, the impact on maximum bullet velocity is generally negligible, especially for effective rounds. Even at high speeds, such as 80 mph, the difference in velocity is minimal except for the slowest bullets. Additionally, air resistance can counteract any potential advantages gained from initial speed. Overall, while initial speed has an effect, it is not significant enough to impact the effectiveness of the round.