Image: 29 Grain .22 on the left. 40 grain .22 on the right
Earlier this year I wrote an article about recording the sound of subsonic bullets using 40 caliber ammunition and learned a lot about the physics and technical aspects of these bullets. Since then I have recorded hundreds of subsonic bullets using smaller 22 caliber ammunition. Keep in mind I am no physics or ammunition expert but since talking with many knowledgable people about subsonic ammunition and actually recording them I have learned even more.
Without going into the boring and extensive details of this process I can can reveal some of the things I’ve learned and experienced. First is that every bullet sounds completely different. I’ve been working mainly with 710 feet per second 22 caliber 40 grain and 29 grain ammunition. The term grain is used to measure the weight of the slug that comes out of the gun. The smaller the number the lighter the projectile is. In a nutshell the 29 grain bullet tends to become very unstable shortly after it leaves the barrel of the gun. It’s using approximately the same amount of powder as the 40 grain but is rounder and tends to start wobbling quicker. Because of this it makes a completely different sound than the 40 grain slug. It also can go off course more easily and can be unpredictable. I’ve shot at the same spot with the same type of 29 grain bullet and it always sounds different. The sound it makes is more like a fast twirl than a ricochet unless it falls to the ground in front of the microphone and bounces off the ground.
The Second thing I learned is the 40 grain bullet makes a better typical ricochet sound than the 29 grain. The slug is heavier and more oval shaped than the 29 grain so it is stable for longer distances before it starts to wobble. It also breaks apart into bigger pieces and that is what makes some ricochets sound really interesting.
This audio demonstration includes both types of ammunition played back at 60% or 50% of normal speed to show in greater detail the differences between the grain size. Also included are some 40 grain bullets bouncing off the surface of water from a 150 meters and a 40 grain bullet that seemed to ricochet straight up upon impact of the boulder and then the slug falls back to the ground right to the side of the MKH-8040ST microphone rig. Enjoy! -Frank
Check out Bullets HD Pro SFX Library for more sounds. The original sounds from this blog post are included in the Beta 2 release out now.
MKH-8040ST in the rocks
MKH-8040ST and MKH-416
MKH-416 and MKH-8040 in front of the boulders
MKH-8040ST over water, yikes!
All images and sounds copyright 2012 Frank Bry – Creative Sound Design