For those of you lucky enough to be able to browse TTAG at work and watch a YouTube video like the one above, I hope the audible difference between supersonic and subsonic ammo when shooting through a suppressor comes through. The only difference being, of course, the actual sonic boom of the bullet — the “CRACK” of it breaking the sound barrier on its flight downrange. It’s a lot louder than one might expect, and is actually much louder than I can capture on video, as. . .
the truth is microphones on cell phones and videos cameras max out between 90 and 110 dB. While my camera in this configuration won’t dampen or scale down audio after a volume spike, the sonic boom absolutely maxes it out. In a lot of calibers it’s actually uncomfortable to shoot supersonic ammo without ear protection, whereas a subsonic load with the same powder charge can be barely noisier than the sound of the action cycling.
In real life, the difference is even more pronounced than in the video.
As I have seen many comments on other videos and elsewhere online suggesting that the difference is actually due mostly to the higher power and pressure of supersonic loads:
- In the video, the exact same ammo shot through the Remington 597 HB .22 LR rifle is fired through the Walther PPQ .22 pistol. While the sub/super difference is massive in the 597, both ammo brands stay subsonic in the short pistol barrel and the two are completely indistinguishable from each other.
- It is true in many cases — for example .300 BLK and many .22 LR brands — that subsonic ammo and supersonic ammo are loaded to entirely different power specs. However, many calibers and brands of ammo achieve subsonic velocity by simply using a heavier projectile that doesn’t go as fast even with the same power and pressure behind it. This becomes extremely apparent when you take the exact same round and find that it’s supersonic in your 7.72″ bbl CZ Scorpion Evo and subsonic through a 4.5″ bbl pistol.
- You can hear the sonic boom travel downrange. The echo and the crack follow the bullet. It’s a readily apparent difference vs. the sound coming from the gun.
Although the following video was just meant to be chronograph testing of the American Eagle “Suppressor” ammo, it’s queued up here to start at a similar subsonic/supersonic audio test: