[marktwain]

The transition zone from subsonic to supersonic was easily detected through the use of a suppressor.

[Eagles6]

For those not wanting to go the suppressor route, subsonic .22lr is surprisingly quiet in it’s own right.

[Red Badger]

[Lurker]

Interesting work, Dean.

Thanks.

L

[Paal Gulli]

This jives with data published by Alan C Paulson about 30 years ago based on tests begun in the early 90s.

From the 1992 joint suppressor project conducted in Finland:

"...The development of whiplash noise does not begin abruptly at velocity Mach 1.0, but gradually, when the velocity of a rifle caliber projectile is more than Mach 0.90....

The Finns are big on suppressors because their snipers were so effective with them in the "Winter War" against the USSR in 1939-40. They have a saying, "The silencer doesn't make the sniper silent, but it does make him invisible."

In a nutshell, it isn't about how fast the bullet is going, it's about how fast the air has to move to get out of the bullet's path. As the speed of sound approaches, "compressibility" comes into play and air behaves stiffer, less springy, and moves more abruptly when getting out of the projectile's path.

This also goes to the point that the bullet has absolutely no response to crossing the speed of sound. It responds progressively as it enters and then leaves the transonic region, but absolutely nothing of note happens at the instant the bullet slows to exactly the speed of sound.

[e_castillo]

Good info.