ORIGINAL: Paul L Mohr
There is no way you heard the target impact from a centerfire at 100 yards let alone 40 yards. I don't know what you thought you heard, but it was not the bullet hitting the target. At those distances the bullet is still traveling 3 times to twice the speed of sound. The bullet is in the target before you are done hearing the muzzle blast of the gun.
I highly doubt you can hear the bullet moving down the barrel of a slug gun either.
Paul
I used to have a pair of the elecrtonic ear protectors and they would block outt eh report of the rifle but sometimes on very rare occasion i would hear some weird zippy sounds like he just described. As for hearing the bullet hit from a centerfire at 100 yards i would belive it from something slow like a 45-70 but not anything with speed to it.