Bullet Velocity: How Fast Is It Really Going
When we measure the velocity of a bullet leaving the handgun this is termed as the Muzzle Velocity and it is measured in feet per second. There are many factors that will dictate the muzzle velocity of ammunition such as the projectile weight, caliber and powder charge. For example a 115 grain 9mm FMJ will have a Muzzle Energy of 356 ft/lbs which will give us a Muzzle Velocity of 1180 ft/sec. So when I tell someone the velocity of a projectile in feet per second they say ok but really how fast does a bullet travel. When we think of speed we are accustom to thinking in miles per hour not feet per second. So let convert ft/sec to m.p.h.
To convert feet per second to miles per hour we need to know two things, how many seconds in one hour and how many feet in a mile. There are 3600 seconds in one hour and 5280 feet per mile. Now we can dust off the math skill and figure out the conversion. MPH = (V * 3600)/5280 that is Miles Per Hour will equal the Muzzle Velocity times 3600 seconds/hour divided by 5280 miles per hour. We stated that a 9mm 115 grain FMJ would have a muzzle velocity of 1180 feet per second, now let convert:
MPH = (1180 * 3600)/5280 MPH = 805
We now can see that our 9mm example is traveling around 805 miles per hours. Now the average person can relate to the velocity of a bullet and the typical response is wow that’s fast. Now lets set another reference point and that is the speed of sound which is approximately 1130 feet per second or:
MPH = 1130*3600/5280 MPH = 771
The speed of sound is approximately 771 miles per hour and any muzzle velocity that is over 1130 feet per second is traveling faster than the speed of sound. If we compare a larger and heaver round such as the .45 ACP we will generally expect a slower velocity and there are some .45 round that travel at faster velocities. Let say we have a 230 grain .45 ACP FMJ with a muzzle energy of 365 ft/lbs, which gives us a muzzle velocity of 845 ft/sec. We know this a subsonic round because the velocity is less than 1130 ft/sec and converting to mph we get:
MPH = (845 * 3600)/5280 MPH = 576
This now puts ammunition velocity into perspective and in general when ask how fast does a bullet travel we can safely say lethally fast. A good website to check out different ammunition velocities is http://www.ballistics101.com and sorry about the math but it had to be done.
Quote of the Day:
“Among the many misdeeds of British rule in India, history will look upon the act depriving a whole nation of arms as the blackest.”
– Mahatma Mohandas K. Gandhi
Guest Instructor/Former Navy Corpsman