What is Subsonic Ammo?
Subsonic ammunition is simply ammo that when fired, is going slower than the speed of sound. The speed of sound is not a static number and will vary. The baseline number is around 1150 feet per second. You know what Sub-sonic ammunition is now, how is Sub-sonic ammunition made. There are two ways to get subsonic ammo. First is to decrease the amount of propellent in the case. While this method will work it should only be done by an experienced reloader and it is much easier and you get increased stopping power by just increasing the weigh of the bullet. The most obvious example of subsonic ammo is the 45 ACP. When the 230 grain bullet is used the bullet will only fly 830 ft/sec (avg), but the title of this blog is 9mm Sub-sonic ammo not 45 ACP ammo. So how do you make 9mm ammo subsonic? The same principle as the 45 ACP is applied. By increasing the weight of the bullet from the standard 115 or 124 grain bullet, up to a 147 grain bullet even the speed of the 9mm can be reduced to sub-so