Fieldcraft Countersniper math

[SMM123]

I have been told, and read, that if you start counting from the time of an incoming bullet impact/passing, until the sound of the firing rifle's report, that each second elapsed accounts for about 300 yards. Because I have never been shot at (fortunately) from any great distance to test out the theory myself, I can only resort to math.

For a given set of atmospherics, a bullet traveling at 2600f/866yps muzzle velocity will impact/pass a position 600 yards away in about .86 seconds, and the sound will travel at about 360yps arriving in about 1.67 seconds. This only allows for less than one second between the bullet and muzzle report passing the same position.

So which is right and why? Or is my math wrong?

 

[TheGerman]

For this math to work, you need a Countersniper scope.

 

[SMM123]

For this math to work, you need a Countersniper scope.

I post my first question, and this is the response. I bet you thought it was funny, even though is was not funny any of the other times it was used.

 

[TheGerman]

Just trying to help.

If you're not open to doing this the right way, the only other thing I can think of is for you to get a friend, bring your sniper rifle and make sure your friend wears his ghillee suit or this will totally not be accurate.

Than have him shoot at you from a known distance and you, with your stopwatch, record it and verify your numbers.

 

[TOP PREDATOR]

think about it for a second (no pun intended)...

if one is "hearing" a bullet going past you, or for that matter hitting anywhere in one's general area, is anyone going to start counting 1 Mississippi or worrying about the load just dropped in the shorts?

lets say the original question and answer is true and one has actually started counting 1 Mississippi....which direction did the shot come from?....i'd rather use my 1.67 seconds to find better cover.

what if there is wind distorting the sound a bit?

what if it's suppressed fire?

what if you forgot your stopwatch?

what if the caliber isn't what you expected to be throwing off any math by a different velocity?

if it is the caliber you expect, velocity starts getting scrubbed off after the muzzle, adding to the invalidity of any formula or even a "rule of thumb". at any given distance the time of flight would differ.

whomever told you that this is applicable in any field condition - stop listening. where ever you read it, throw that book away before someone gets hurt.

your math is probably correct though, and that noise passing by may have been a hummingbird.

 

[TOP PREDATOR]

4 cents: i don't think paint balls can go 2600fps

 

[SMM123]

think about it for a second (no pun intended)...

if one is "hearing" a bullet going past you, or for that matter hitting anywhere in one's general area, is anyone going to start counting 1 Mississippi or worrying about the load just dropped in the shorts?

lets say the original question and answer is true and one has actually started counting 1 Mississippi....which direction did the shot come from?....i'd rather use my 1.67 seconds to find better cover.

what if there is wind distorting the sound a bit?

what if it's suppressed fire?

what if you forgot your stopwatch?

what if the caliber isn't what you expected to be throwing off any math by a different velocity?

if it is the caliber you expect, velocity starts getting scrubbed off after the muzzle, adding to the invalidity of any formula or even a "rule of thumb". at any given distance the time of flight would differ.

whomever told you that this is applicable in any field condition - stop listening. where ever you read it, throw that book away before someone gets hurt.

your math is probably correct though, and that noise passing by may have been a hummingbird.

I have a few friends who are ex-mil snipers, who quoted this to me, who were taught it at some point. It never did add up for me, so I am questioning the data, and they could not confirm the math. Being that they are all combat veterans, I am not about to stop listening.

The History Channel documented a case where this was detailed by a USMC sniper, whom I can only assume found the opposite of your assertion in field conditions.
If you don't want to watch the full documentation, just skip to 7:50 and watch until about 9:00.



...waiting for more witty comebacks, since that is all people seem to have around here to answer relevant technical questions...

 

[EasyGravy]

Lotta eyes arround, and its not hard to get a quick read ln report. Someone usually calls or sees it and calls it

 

[--BLACKOUT--]

I remember watching that show. They had been shot at once or twice before by the same shooter. So, when they did make the count they already knew what was being fired at them. They figured approximately where it was from and the shooter went back to the exact same place as his previous shot and took one for the team for shooting from the same place twice. Seems like there is too many variables to deal with it on the first shot. How often would you get the same circumstances as the guys in the documentry.

 

[SMM123]

I remember watching that show. They had been shot at once or twice before by the same shooter. So, when they did make the count they already knew what was being fired at them. They figured approximately where it was from and the shooter went back to the exact same place as his previous shot and took one for the team for shooting from the same place twice. Seems like there is too many variables to deal with it on the first shot. How often would you get the same circumstances as the guys in the documentry.

Who cares?! I am not asking about a scenario, nor contemplating getting into a sniper/counter sniper gun battle. I am not asking about secret squirrel shit either, nor contemplating the use of stop watches in the field.

My question is simple and based on the actual math of distance, time, and velocity vs. what some people have been taught. It is about the truth (and a brain exercise.) Without questioning the validity of what someone says to be a supposed truth, i.e.: approximately 300 yards per second, then how can we find the truth, regardless of whether it will ever happen or not. That is not the point.

 

[SMM123]

................

 

[--BLACKOUT--]

Just trying to help.

If you're not open to doing this the right way, the only other thing I can think of is for you to get a friend, bring your sniper rifle and make sure your friend wears his ghillee suit or this will totally not be accurate.

Then have him shoot at you from a known distance and you, with your stopwatch, record it and verify your numbers.

I guess you missed this reply then. Here is your answer, let us know how it turns out.

 

[dieselgeek]

At 1000 yards, you can hear the report before the bullet passes with my 300 blackout.

 

[TheGerman]

Serious answer from actual experience:

If you're waiting to hear a rifle shot to A. find the guy you are 'countersnipering' and B. figure the distance you are probably dead or will be shortly.

Chances are if something out there shoots, its because you didn't know it was there. Why? Because otherwise you would have ranged and engaged him already. This is why you're taught to always assume, regardless of how safe/in the rear/dug in/whatever that you are being observed or are 1 too quick movement of your arm or head away from being observed.

Additionally, you cannot take that math and apply it everywhere. Places where you are shooting into or out of a valley, extreme up or down angle shots, echo off terrain, wind and 100 other random variables will make your math more guesswork than anything.

 

[Jared91]

Here ya go. Vid taken at 300yd range

https://www.youtube.com/watch?v=mr3UCU9WxGI&feature=youtube_gdata_player
sent from Jennifer Lawrence's bedroom

 

[hessian]

Maybe the speed of sound is constant and the speed of the bullet is constantly decreasing.

 

[Jared91]

Maybe the speed of sound is constant and the speed of the bullet is constantly decreasing.

Don't go and throw physics in here, now

sent from Jennifer Lawrence's bedroom

 

[SMM123]

Serious answer from actual experience:

If you're waiting to hear a rifle shot to A. find the guy you are 'countersnipering' and B. figure the distance you are probably dead or will be shortly.

Chances are if something out there shoots, its because you didn't know it was there. Why? Because otherwise you would have ranged and engaged him already. This is why you're taught to always assume, regardless of how safe/in the rear/dug in/whatever that you are being observed or are 1 too quick movement of your arm or head away from being observed.

Additionally, you cannot take that math and apply it everywhere. Places where you are shooting into or out of a valley, extreme up or down angle shots, echo off terrain, wind and 100 other random variables will make your math more guesswork than anything.

Now I feel like you might actually be trying to help, but you are still missing the point. You are hypothesizing things that I am not including for a reason: because it does not matter in the math!

Math is not guesswork. Math does not care if your head took a bullet or not. Math does not care if you are dug in, behind a wall, observant, or chewing your cud. None of this pertains to my question. I was not making my query in the hypothetical, which everyone continues to interject here. My question was based on math that is absolute for a given circumstance which I plainly stated. Changing the variables is not a help for the purpose of verification. If military snipers are taught that 1 second is roughly equal to 300 yards distance, yet my math states differently, I am looking for verification on either the math, the training, or some other science that proves or disproves one or the other.

I am starting to think this site if full of government trolls, hell bent on derailing threads or providing the least amount quality information possible.

 

[Rhyno]

Maybe the speed of sound is constant and the speed of the bullet is constantly decreasing.

Speed of sound isn't constant though.

 

[SMM123]

Maybe the speed of sound is constant and the speed of the bullet is constantly decreasing.

I accounted for that. There is about .25 second difference between a constant 2600fps in a vacuum and decreasing velocity in atmospherics to 600 yards.

.69 sec @600 with no atmospherics
.86 sec @600 with atmospherics (at my elevation, temps, humidity, etc.)

So that does not make up the differences I am seeing, mathematically. And my speed of sound calculations are at the same atmospherics.

 

[Jared91]

Speed of sound isn't constant though.

Unless there are rapid changes and differences in temp/humidity/ air density over that distance, which is unlikely, it still wouldn't be much of, if any difference. You're looking at elr distances for that to take effect

sent from Jennifer Lawrence's bedroom

 

[Rhyno]

Unless there are rapid changes and differences in temp/humidity/ air density over that distance, which is unlikely, it still wouldn't be much of, if any difference. You're looking at elr distances for that to take effect

sent from Jennifer Lawrence's bedroom

That still doesn't make it a constant.

 

[Redmanss]

The crack-thump method gives you a SWAG at distance to shooter, but is hardly anything scientific that can be applied on a two way range by a human. Your result is "he's out there a ways" or "you sneaky mother fucker". How do you know what just shot at you? Was it x39 or x54? Big difference in velocities and TOF there and I've never been able to tell the difference at anything of any real range. The best sort of training for this is actually from weeks upon weeks pulling targets in the pits, you get the rhythm down after a while, for a particular setup at least but it gives you an idea.

Still though, it's all just a guess and your observation skills have to accomplish the rest. That's why DARPA is playing with cool electronic Doppler type shit. Counter-Sniper Program (C-Sniper)

 

[sharac]

Perhaps you should take into account that many things military teaches have more to do with keeping up morale (albeit based on false facts or futile goals) than with surviving or overcoming problems encountered in battlefield. The best advice given (counting 1Mississipi while making sure that somewhere at first double S you are safely hidden behind solid obstacle) was completely ignored by you and still persisting in "accurately" measuring distance or god forbid location of the "sniper" who just missed you and has (while you were chanting 1Miss...) already chambered next round and will probably correct his "math" to make sure you don't hear bullet go by next time.

But yeah sure you can do your math i just don't know how well your measurement system work (how consistent are you with 1Mississipi, will you account for atmosphere? when will you start counting before or after you piss yourself, how full is your bladder - in reference to pisstime etc..) so "your results may vary ".

I hope you get it? All your math is waste of precious time as obviously shooter is there somewhere and if he is @411m or @550 makes little difference at that particular moment you've heard him miss.

 

[wilwith1l]

Time doesn't work the same way in a gunfight as it does in other places, if you're trying to count it out in your head atleast.

 

[Papa Zero Three]

Good God. Why is it the Math people always have the hardest time understanding what a "field expedient" or rule of thumb method implys(Rhetorical question)?

Spend some time in the pits and you will have all the experience you need to guage this "by ear". It's a rule of thumb and an estimation at best. Trying to match it up to a mathamatical, on paper calculation is an academic mental masturbation exercise as there are other variables in an environment that aren't factored for in a pure mathematical equation. Getting shot at in the PITS vs gettiing shot at in an urban environment, direction of the sniper to the target and any other environmental factor makes this extremely hard even for electronic shot detection systems to accurately determine. At best, it will give you a direction but to think it will give you an accurate distance is again, faulty logic. It's a rule of thumb method (have I said that before?).


For the OP here is a video that attempts to address your question with mathamatics and practical in field video. It's AMAZING what a little Google-Fu can do for you.

 

[iShoot17]

I do believe most of the above posts certainly answer the question at hand, especially those with real experience.

The crack thump method is too much of a 'vacuum' idea. In a perfect world, where all snipers used the exact same caliber rifle, loaded to the exact specs, shot from the exact same weapon system, under the exact same environmental standards, with no human error, hypothetically, yes, the crack thump method would work SHOULD work, to an approximate amount.

However, when looking at the above statements about being in the pits, the fact that a sniper who misses one shot will be DOPED in for the next shot before you finish counting, all specs are not the same for all rifles, bullets, and projectiles, and human error is a significant issue in every task in life, then no, the crack thump is not truly a probably method of ranging. A human is not capable of counting to the .xx of a second at a definitive point in time. To elaborate, no human is going to see the splash of a bullet and instinctively begin to count by the .xx of a second. The 'that sneaky mother fucker' comment, after just dropping a load in your skivvies will have already taken up a split second. Or the natural instinct of to get further behind cover will take a split second. Then you're stuck at 1.5x of a second, rather than the 2.xx of a second it truly was. According to your hypothesis, of approximately 300 yards per second, this leaves you with a disadvantaged 450yard SWAG compared to the true 600y range. Another fatal flaw added to the list.

Do you see all of the points being made above? In a vacuum, with all variables known, calculations already started, and a robot to begin counting to even the .xxxx of a second, and with the agreed upon "I shoot once and won't move, then you shoot once and don't move" method by both snipers, then yes, it is highly likely that the method you are question would work; however, in real life, when we are not in a vacuum, all variables are NOT know, and human error is playing a key factor (i.e. The sniper shooting at you missed due to human error. The system was capable of making the shot, but due to a miscalculation somewhere (distance, wind, etc) he missed his shot because of human error) then no, the method is not likely to be successful.

 

[Coloradocop]

I think the answer is really found through simification of this thought process. For all of the reasons mentioned above, estimating time accurately while being shot at can be very difficult. However, it's simple enough to know that the longer the time between the two sounds, the further it was fired from your location, all else being equal.

 

[Jig Stick]

wheres Lindy

 

[LawnMM]

Serious question, are you LE/MIL? What likelihood is there of you being shot at by a high power rifle from long distance?

 

[EasyGravy]

People playing too many video games. He must be trying to vet up

 

[kmussack]

Flash Bang being confused with Crack Thump......two completely different things.

Lightning strike followed by thunder. Light arrival is instantaneous sound arrives at a speed of 300-meters per second. So if it takes a "four count" to hear thunder after the lightning struck; 4x300=1,200 meters away.

Crack Thump is like a race between the tortoise and the hare. Muzzle blast sound travels on constant 300-meters per second (generally).

Time of flight of the bullet is different depending upon the distance traveled and deceleration.

The interval between Crack and Thump even at 1,000-yards is so small as to be almost useless for determining range to the shooter by ear.

 

[lancetkenyon]

Shooting 497 yds. open sights with a 16" M4
.223 w. 55gr. Varmageddon @ 2610FPS muzzle vel.
Slows to 1076fps+/- @ 500yds. (speed of sound would have been approx. 1123fps. that day)
TOF is .92 seconds.
Elevation was approximately 3700' AMSL
Baro was 29.91
Temp was about 65° F.
Relative humidity was about 20%
Shooting from west to east

You can see the hit on steel, then count the time of the "ding" back to us.

 

[kmussack]

...You can see the hit on steel, then count the time of the "ding" back to us....

That's an example of "Flash-Bang" not "Crack-Thump". (visible/audible not audible/audible)

 

[lancetkenyon]

That's an example of "Flash-Bang" not "Crack-Thump". (visible/audible not audible/audible)

Wouldn't that still be counting back the speed of sound? Just from the impact of bullet vs. the report of rifle?

I'm just saying, without high tech equipment, starting the time from the exact moment of impact until hearing the report or impact would yield way too many errors. And not knowing velocity (at muzzle and target), site conditions, etc. it would be near impossible to tell actual distance.

Also, stating almost exact numbers in my list, and yardage, and I would bet someone still could not listen to the sounds and get accurate numbers. You could also listen to the report of the rifle, and count off to the impact, then count back to the sound of impact.

Just my opinion. I couldn't do it.

As for "Crack-thump" (audible-audible), I would think a round impacting near you would be nearly instantaneous audible, close enough to visual.

 

[jim_k]

At 700 yards, almost all bullets take 1 second to get there from the muzzle. Sound takes 2 seconds, so the difference is 1 second. Still, it's hard to measure accurately. At 1,000 yards, TOF about 1.5 seconds, maybe a little more, and sounds arrives after total 3 seconds, or 1.5 seconds later. An error of ½ second can't tell the difference between 700 and 1,000 yards. As mentioned before, it's really either "real close" or "pretty far off," as far as calculating location of the shot. I think better shot localization is done by listening to a lot of shots, taking wind and caliber into account, and estimating distance, then verifying when able; which is to say experience. Stay on the road at your local rifle range, behind the firing line, and take wind and caliber into account, and get a feel for the sound of the muzzle blast at various distances.
Jim

 

[thejeep]

How about you test your theory pitting sound against sound. Your question asks how far away is the shooter based on the bullet impact at your location and you hearing the report at your location.

Let's assume speed of sound is constant. Shoot a gong at known distance. The amount of time it takes you to hear the gong should be equal to the time it takes the gong to hear your report. Right? If the speed of your muzzle blast is the same speed as the ring of steel.