How close do you have to be to a bullet to hear it go by?

[JohnRich 4]

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You first have to know the velocity of the bullet. You may have some idea of the muzzle velocity if you know your enemy's weapons.

Most combat rifles have a muzzle velocity of between 2500 and 3200 fps. Since we're only guesstimating, that's not a wide enough range to make much of a drastic difference. How fast the bullets decelerate once they leave the barrel depends upon bullet design and bullet weight, and distance.

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If the bullet speed is Mach 2 (say 2000 fps) and you are 2000 ft. from the shooter then you will count only 1 second after the bullet goes by before you hear the gunshot.

To clarify for our readers: It will take the bullet about one second to cover that distance. But meanwhile, the sound of the gunshot from the gun is plodding along at only 1,000 fps, and thus will be heard two seconds later. So, the bullet arrives in one second, and the sound in two seconds, for a delay between the bullet and the gunshot sound of one second.

And to complicate things further - the velocity of the bullet degrades at a non-linear rate, but the velocity of the sound from the gunshot is constant.

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You better be ready with the stopwatch to get an accurate distance assessment. Compensating for the deceleration of the bullet complicates things further.

Right, but when looking for an enemy shooter, it gives you a rough idea of their distance. Then you scan the terrain at that range for places where he might be hiding. It ain't perfect, but it's better than having no clue at all.

My .308 rounds go from about 2,800 fps at the muzzle to about 1500 fps at 1,000 yards. And that's at the extreme end of the range of what anyone shoots a .308. At more normal distances, the deceleration isn't anywhere close to that. And once you've heard the variance between bullet crack and gunshot boom at different distances, your ears get attuned to it, and can tell the difference. I have them figured out for 200, 300, 600 and 1,000 yards because of my match shooting. You can't tell much difference between 200 & 300, but between 300, 600 and 1,000 is easily noticeable.

[muff528 3]

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You first have to know the velocity of the bullet. You may have some idea of the muzzle velocity if you know your enemy's weapons.

Most combat rifles have a muzzle velocity of between 2500 and 3200 fps. Since we're only guesstimating, that's not a wide enough range to make much of a drastic difference. How fast the bullets decelerate once they leave the barrel depends upon bullet design and bullet weight, and distance.

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If the bullet speed is Mach 2 (say 2000 fps) and you are 2000 ft. from the shooter then you will count only 1 second after the bullet goes by before you hear the gunshot.

To clarify for our readers: It will take the bullet about one second to cover that distance. But meanwhile, the sound of the gunshot from the gun is plodding along at only 1,000 fps, and thus will be heard two seconds later. So, the bullet arrives in one second, and the sound in two seconds, for a delay between the bullet and the gunshot sound of one second.

And to complicate things further - the velocity of the bullet degrades at a non-linear rate, but the velocity of the sound from the gunshot is constant.

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You better be ready with the stopwatch to get an accurate distance assessment. Compensating for the deceleration of the bullet complicates things further.

Right, but when looking for an enemy shooter, it gives you a rough idea of their distance. Then you scan the terrain at that range for places where he might be hiding. It ain't perfect, but it's better than having no clue at all.

My .308 rounds go from about 2,800 fps at the muzzle to about 1500 fps at 1,000 yards. And that's at the extreme end of the range of what anyone shoots a .308. At more normal distances, the deceleration isn't anywhere close to that. And once you've heard the variance between bullet crack and gunshot boom at different distances, your ears get attuned to it, and can tell the difference. I have them figured out for 200, 300, 600 and 1,000 yards because of my match shooting. You can't tell much difference between 200 & 300, but between 300, 600 and 1,000 is easily noticeable.

Yes, to all that. In a roundabout way I was only trying to point out that the differences in "time delays" between bullet sound and gunshot sound are only fractions of seconds for significant differences in distances between the observer and the shooter. Degradation of the bullet speed will only make the time delays "tighter" as the constant speed wave front is "outrun" decreasingly by the bullet. All that has to be calculated in your head while being shot at. My guess is you are not doing the math in your mind, but rather instinctively guessing the distances based on experience. Kinda like a quarterback is not actually doing calculus in his head when throwing a pass downfield to the wide receiver. Bad analogy but all I got at 6:45 am.

[steve1 5]

Another sound that hunters often hear is the bullet hitting meat. At closer ranges you can't hear this, but at longer ranges you can.

My wife killed an elk this past fall. There was a herd of about 12 elk standing on a distant ridge. She layed down, got a good rest, and shot. I listened closely for the sound of that bullet. If it had been a miss their would have probably been little or no sound. Sure enough, you could hear a distant thump of the bullet hitting home.

I didn't see the elk go down, but I knew she had hit an elk. I told her to wait before she shot again. We didn't want more than one elk. Neither of us could tell which elk she had just shot at, but I knew one was hit.

We hiked over there, and sure enough a big cow was laying dead.

When I was a kid, hunting gophers, I could tell a gut shot from a hit somewhere else, just by the sound of the bullet hitting.

Being aware of those sounds can make you a better hunter....

[JohnRich 4]

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In a roundabout way I was only trying to point out that the differences in "time delays" between bullet sound and gunshot sound are only fractions of seconds for significant differences in distances between the observer and the shooter. Degradation of the bullet speed will only make the time delays "tighter" as the constant speed wave front is "outrun" decreasingly by the bullet. All that has to be calculated in your head while being shot at. My guess is you are not doing the math in your mind, but rather instinctively guessing the distances based on experience. Kinda like a quarterback is not actually doing calculus in his head when throwing a pass downfield to the wide receiver. Bad analogy but all I got at 6:45 am.

Correct! You can sit down and do the math, and then observe it in the field to confirm. But that real-world repeated experience gives you the instinct to recognize and know intuitively, instantaneously, what the time delays mean. Just as an experienced skydiver develops an internal clock to know instinctively when it's time to break-off to pull, without actually looking at an altimeter or stopwatch.

[skydiver30960 0]

Heh. Sorry all, I TOTALLY spaced on this thread. I don't spend much time in SC, and when I posted it here I never came back to check on it until I just remembered I put it here. Sorry to post and run!

SO, as I mentioned in the OP, it was YEARS ago. So, WRT sub- vs. supersonic, I really don't recall if it was "BANG... -zip-" or "-zip-...BANG". All I recall is that I heard both. If I hadn't heard the report I never would have thought that sound was a round going by. Sorry I can't give more info.

So, my question related more to how close the round was when it went by me (or my head, if that's more appropriate) rather than how close the shooter was to me when he fired the shot.

Thanks, and SO sorry for the delay in clarafication!

Elvisio "SC = unfamiliar territory" Rodriguez