The speed of a .556 bullet can vary depending on several factors such as the specific load, barrel length, and environmental conditions. However, the standard velocity for a .556 NATO round, commonly used in rifles like the AR-15, is around 3,000 feet per second (fps).
To convert this speed to miles per hour (mph), we can use the conversion factor of 1,760 yards per hour in a mile. Therefore, the approximate speed of a .556 bullet would be:
3,000 fps * (1 mile / 5,280 feet) * (1,760 yards / 1 mile) * (1 hour / 3,600 seconds) ≈ 3,409 mph
So, a .556 bullet typically travels at around 3,409 miles per hour. It's important to note that this is an approximate value and can vary depending on the specific load and firearm used.