I am a british sniper passed my course in october last year and leaving for Afghanistan in three weeks. My commander is under the impression that barrometric pressure isnt going to be an issue while we are there, I thought this was a bit odd as I was under the impression that the longer your shots are then barometric pressure certainly will come into play. Can someone please answer my question and explain if it does effect the round and also what effect does it have on the round. thankyou all
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Range Report Barrometric pressure
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Re: Barrometric pressure
Barometric pressure will certainly affect the round just as you suppose. I believe the problem comes down to "Corrected Pressure" and "Station Pressure". If your commander is looking at the weather in London the BP will be 29.4 mmHg and if he looks on line at Kabul it will also be 29.4 mmHg. The problem is that they are at different altitudes and are corrected. The station pressure in London may very well be 29.4 mmHg but in Kabul it's more than likely around 24.5 mmHg. Plug those numbers into your ballistic calculator with both at elevation = 0 ft/meters and you will see the difference in performance.
Cheers & Good Hunting,
Doc
Barometric pressure will certainly affect the round just as you suppose. I believe the problem comes down to "Corrected Pressure" and "Station Pressure". If your commander is looking at the weather in London the BP will be 29.4 mmHg and if he looks on line at Kabul it will also be 29.4 mmHg. The problem is that they are at different altitudes and are corrected. The station pressure in London may very well be 29.4 mmHg but in Kabul it's more than likely around 24.5 mmHg. Plug those numbers into your ballistic calculator with both at elevation = 0 ft/meters and you will see the difference in performance.
Cheers & Good Hunting,
Doc
Re: Barrometric pressure
I remember Robert Furlong explaining the gain in effective range of his Tac-50 according to 3 causes in Agfghanistan.. Generaly high altitude in the region he was engaging his target, relativly low humidity level compare to Canada and he like how "hot" the US ammo were compare to what he was used to shoot.
That said, I guess you are supply a portable barometric measurement tool right? So no matter where you will be deploy, you could check the pressure...
I remember Robert Furlong explaining the gain in effective range of his Tac-50 according to 3 causes in Agfghanistan.. Generaly high altitude in the region he was engaging his target, relativly low humidity level compare to Canada and he like how "hot" the US ammo were compare to what he was used to shoot.
That said, I guess you are supply a portable barometric measurement tool right? So no matter where you will be deploy, you could check the pressure...
Re: Barrometric pressure
A lot of ballistic programs use DA density altitude to calculate the dope,kestrel model 4500 I think has DA reading capabilities
I suggest you take a look at Adaptive FDAC. (actsvirginia.com),it is pretty accurate, watch LL's video it is posted on their site.
Fight smart, Stay safe.
A lot of ballistic programs use DA density altitude to calculate the dope,kestrel model 4500 I think has DA reading capabilities
I suggest you take a look at Adaptive FDAC. (actsvirginia.com),it is pretty accurate, watch LL's video it is posted on their site.
Fight smart, Stay safe.
Re: Barrometric pressure
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: twinturbo</div><div class="ubbcode-body"> Ck out www.kestrel.com </div></div>
I think this is what you meant...
http://www.nkhome.com/kestrel/
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: twinturbo</div><div class="ubbcode-body"> Ck out www.kestrel.com </div></div>
I think this is what you meant...
http://www.nkhome.com/kestrel/
Re: Barrometric pressure
If you look on thief bay in the UK there are some 4000 series Kestrel up very cheap (cancelled military contract).
I am seriously surprised that you OC isn't significantly more knowledgable on barometric pressure effects?
The baro shifts on stickledown during courses especially at 1000yds certainly are good indicators on how important this is.
If you look on thief bay in the UK there are some 4000 series Kestrel up very cheap (cancelled military contract).
I am seriously surprised that you OC isn't significantly more knowledgable on barometric pressure effects?
The baro shifts on stickledown during courses especially at 1000yds certainly are good indicators on how important this is.
Re: Barrometric pressure
per Wikipedia
Lowest point in A-Stan is 258 meters MSL
highest point in A-Stan is 7,492 meters MSL
UK uses milibars or mmHg?
per Wikipedia
Lowest point in A-Stan is 258 meters MSL
highest point in A-Stan is 7,492 meters MSL
UK uses milibars or mmHg?
Re: Barrometric pressure
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Emouse</div><div class="ubbcode-body">I am seriously surprised that you OC isn't significantly more knowledgable on barometric pressure effects? </div></div>
Sorry man but when I read this I got a little laugh, I guess you have never been in a Sniper Section.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Emouse</div><div class="ubbcode-body">I am seriously surprised that you OC isn't significantly more knowledgable on barometric pressure effects? </div></div>
Sorry man but when I read this I got a little laugh, I guess you have never been in a Sniper Section.
Re: Barrometric pressure
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MarcC11B</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Emouse</div><div class="ubbcode-body">I am seriously surprised that you OC isn't significantly more knowledgable on barometric pressure effects? </div></div>
Sorry man but when I read this I got a little laugh, I guess you have never been in a Sniper Section. </div></div>
Things are a little different this side of the pond,...its not usual for a slip in basic knowledge like that here!
Even the OP was surprised.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MarcC11B</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Emouse</div><div class="ubbcode-body">I am seriously surprised that you OC isn't significantly more knowledgable on barometric pressure effects? </div></div>
Sorry man but when I read this I got a little laugh, I guess you have never been in a Sniper Section. </div></div>
Things are a little different this side of the pond,...its not usual for a slip in basic knowledge like that here!
Even the OP was surprised.
Re: Barrometric pressure
Basic knowledge for you and I maybe, but my officers/commanders wouldn't know what the hell you are talking about. As far I'm concerned they can stay in their lane and out of mine. The less they know the more of an SME I am and the less they micro manage.
Basic knowledge for you and I maybe, but my officers/commanders wouldn't know what the hell you are talking about. As far I'm concerned they can stay in their lane and out of mine. The less they know the more of an SME I am and the less they micro manage.
Re: Barrometric pressure
AIUK1, barometric pressure has less to do with influencing your ballistics than your station density altitude.
Simply, air is less dense (thinner) the higher you go and puts less drag on your bullet. Every thousand feet altitude you gain is as if you have another inch of barrel length -- your bullet will fly farther for the same launch speed out of the muzzle you had down in Dorset, Bisley, or Salisbury Plain. The same reason it takes a longer take-off or landing run for an airplane at Kandahar air base and a helicopter needs more power and pitch to hover in the Hindu Kush.
Having clueless officers is the reason snipers are never trained nor employed correctly. You can be the most expert SME, but if command doesn't know how to use you you end up being TOC guards.
AIUK1, barometric pressure has less to do with influencing your ballistics than your station density altitude.
Simply, air is less dense (thinner) the higher you go and puts less drag on your bullet. Every thousand feet altitude you gain is as if you have another inch of barrel length -- your bullet will fly farther for the same launch speed out of the muzzle you had down in Dorset, Bisley, or Salisbury Plain. The same reason it takes a longer take-off or landing run for an airplane at Kandahar air base and a helicopter needs more power and pitch to hover in the Hindu Kush.
Having clueless officers is the reason snipers are never trained nor employed correctly. You can be the most expert SME, but if command doesn't know how to use you you end up being TOC guards.
Re: Barrometric pressure
I have the 3500, it reports altitude but not the DA like the 4500 does. from Kestrel, "density altitude is a measure of the density of the air, given in units of distance. It is a function of temperature, relative humidity and air pressure", is there a method in which I can use the data on the 3500 to give a DA outpout?
I have the 3500, it reports altitude but not the DA like the 4500 does. from Kestrel, "density altitude is a measure of the density of the air, given in units of distance. It is a function of temperature, relative humidity and air pressure", is there a method in which I can use the data on the 3500 to give a DA outpout?
Re: Barrometric pressure
ACTS FDAC Cards are most applicable to shooters (with minute or mil corrections), but this is a generic table (used by pilots):
ACTS FDAC Cards are most applicable to shooters (with minute or mil corrections), but this is a generic table (used by pilots):
Re: Barrometric pressure
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">AIUK1, barometric pressure has less to do with influencing your ballistics than your station density altitude.
Simply, air is less dense (thinner) the higher you go and puts less drag on your bullet. Every thousand feet altitude you gain is as if you have another inch of barrel length -- your bullet will fly farther for the same launch speed out of the muzzle you had down in Dorset, Bisley, or Salisbury Plain. The same reason it takes a longer take-off or landing run for an airplane at Kandahar air base and a helicopter needs more power and pitch to hover in the Hindu Kush.
Having clueless officers is the reason snipers are never trained nor employed correctly. You can be the most expert SME, but if command doesn't know how to use you you end up being TOC guards. </div></div>
This has always been my experience with barometrics. It's the last thing I add to the dope if at all. Altitude, wind speed and vector, line of sight angle all figured more prominently for me than barometrics. I have reached the conclusion that for me, I can't hold steady enough to account for the impact change barometric differences cause.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">AIUK1, barometric pressure has less to do with influencing your ballistics than your station density altitude.
Simply, air is less dense (thinner) the higher you go and puts less drag on your bullet. Every thousand feet altitude you gain is as if you have another inch of barrel length -- your bullet will fly farther for the same launch speed out of the muzzle you had down in Dorset, Bisley, or Salisbury Plain. The same reason it takes a longer take-off or landing run for an airplane at Kandahar air base and a helicopter needs more power and pitch to hover in the Hindu Kush.
Having clueless officers is the reason snipers are never trained nor employed correctly. You can be the most expert SME, but if command doesn't know how to use you you end up being TOC guards. </div></div>
This has always been my experience with barometrics. It's the last thing I add to the dope if at all. Altitude, wind speed and vector, line of sight angle all figured more prominently for me than barometrics. I have reached the conclusion that for me, I can't hold steady enough to account for the impact change barometric differences cause.
Re: Barrometric pressure
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1ZNUF</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">AIUK1, barometric pressure has less to do with influencing your ballistics than your station density altitude.
Simply, air is less dense (thinner) the higher you go and puts less drag on your bullet. Every thousand feet altitude you gain is as if you have another inch of barrel length -- your bullet will fly farther for the same launch speed out of the muzzle you had down in Dorset, Bisley, or Salisbury Plain. The same reason it takes a longer take-off or landing run for an airplane at Kandahar air base and a helicopter needs more power and pitch to hover in the Hindu Kush.
Having clueless officers is the reason snipers are never trained nor employed correctly. You can be the most expert SME, but if command doesn't know how to use you you end up being TOC guards. </div></div>
This has always been my experience with barometrics. It's the last thing I add to the dope if at all. Altitude, wind speed and vector, line of sight angle all figured more prominently for me than barometrics. I have reached the conclusion that for me, I can't hold steady enough to account for the impact change barometric differences cause. </div></div>
We don't as a general rule utilise non-qualified officers to run sniper cadres. Hence the surprise at such a basic mistake.
Unlike the U.S we do see 3 seasons in one day here on our ranges,...sometimes significant bara/DA and temp swings along with fast changing wind speeds and vectors/light conditions. Its the very reason why the OP did his test on Stickledown,...because of the difficult shooting conditions that can be experienced.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1ZNUF</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">AIUK1, barometric pressure has less to do with influencing your ballistics than your station density altitude.
Simply, air is less dense (thinner) the higher you go and puts less drag on your bullet. Every thousand feet altitude you gain is as if you have another inch of barrel length -- your bullet will fly farther for the same launch speed out of the muzzle you had down in Dorset, Bisley, or Salisbury Plain. The same reason it takes a longer take-off or landing run for an airplane at Kandahar air base and a helicopter needs more power and pitch to hover in the Hindu Kush.
Having clueless officers is the reason snipers are never trained nor employed correctly. You can be the most expert SME, but if command doesn't know how to use you you end up being TOC guards. </div></div>
This has always been my experience with barometrics. It's the last thing I add to the dope if at all. Altitude, wind speed and vector, line of sight angle all figured more prominently for me than barometrics. I have reached the conclusion that for me, I can't hold steady enough to account for the impact change barometric differences cause. </div></div>
We don't as a general rule utilise non-qualified officers to run sniper cadres. Hence the surprise at such a basic mistake.
Unlike the U.S we do see 3 seasons in one day here on our ranges,...sometimes significant bara/DA and temp swings along with fast changing wind speeds and vectors/light conditions. Its the very reason why the OP did his test on Stickledown,...because of the difficult shooting conditions that can be experienced.
Re: Barrometric pressure
Roger E-mouse, should have specified <span style="font-style: italic">"Uneducated / untrained <span style="text-decoration: underline">US</span> officers"</span> for the poster above my post.
I imagine you can get some fairly good baro swing data and height/angle shots in Wales or up in Scotland.
Roger E-mouse, should have specified <span style="font-style: italic">"Uneducated / untrained <span style="text-decoration: underline">US</span> officers"</span> for the poster above my post.
I imagine you can get some fairly good baro swing data and height/angle shots in Wales or up in Scotland.
Re: Barrometric pressure
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">Having clueless officers is the reason snipers are never trained nor employed correctly. You can be the most expert SME, but if command doesn't know how to use you you end up being TOC guards. </div></div>
Touché
The U.S. Army has always had this problem and probably always will.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">Having clueless officers is the reason snipers are never trained nor employed correctly. You can be the most expert SME, but if command doesn't know how to use you you end up being TOC guards. </div></div>
Touché
The U.S. Army has always had this problem and probably always will.
Re: Barrometric pressure
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">Roger E-mouse, should have specified <span style="font-style: italic">"Uneducated / untrained <span style="text-decoration: underline">US</span> officers"</span> for the poster above my post.
I imagine you can get some fairly good baro swing data and height/angle shots in Wales or up in Scotland. </div></div>
Yes,..Warcop, Sennybridge, Diggle to name but a few have some interesting terrain available. Wworking with extremes of weather that vary throughout a shooting day is the way to learn.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">Roger E-mouse, should have specified <span style="font-style: italic">"Uneducated / untrained <span style="text-decoration: underline">US</span> officers"</span> for the poster above my post.
I imagine you can get some fairly good baro swing data and height/angle shots in Wales or up in Scotland. </div></div>
Yes,..Warcop, Sennybridge, Diggle to name but a few have some interesting terrain available. Wworking with extremes of weather that vary throughout a shooting day is the way to learn.
Re: Barrometric pressure
Here are some things you might like to know about shooting and barometric pressure:
Barometric Pressure and Ballistic Software
Making Ballistic Cards Using Density Altitude
Manual Calculation of Density Altitude
I don't get on here very often - if you have questions, feel free to use the email link on those pages.
Good shooting.
Here are some things you might like to know about shooting and barometric pressure:
Barometric Pressure and Ballistic Software
Making Ballistic Cards Using Density Altitude
Manual Calculation of Density Altitude
I don't get on here very often - if you have questions, feel free to use the email link on those pages.
Good shooting.
Re: Barrometric pressure
Quote from this article: Barometric Pressure and Ballistic Software (http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/Baro/)
"Change the temperature and relative humidty separately, and ensure that the program is changing the output appropriately, remember than a higher temperature should result in a lower required elevation setting for a given shot, and that a higher relative humidity should also result in a lower required elevation setting. "
This sounds wrong to me.... I always thought higher humidity meant more air resistance, thus requiered more elevation to hit the target...
Thanx for these nice articles Lindy!
Quote from this article: Barometric Pressure and Ballistic Software (http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/Baro/)
"Change the temperature and relative humidty separately, and ensure that the program is changing the output appropriately, remember than a higher temperature should result in a lower required elevation setting for a given shot, and that a higher relative humidity should also result in a lower required elevation setting. "
This sounds wrong to me.... I always thought higher humidity meant more air resistance, thus requiered more elevation to hit the target...
Thanx for these nice articles Lindy!
Re: Barrometric pressure
I think the bigger question here is wether the difference in pressures you will be seeing is enough to change your poi such that it changes your effective range.
Higher pressure will slow the bullet faster therefore lower your poi and increase flight time allowing wind to have a larger effect on the bullets trajectory.
For target shooting this is important because you reach the transonic zone sooner and the bullet will tumble but when you are looking at effect kill ranges as a sniper the effect may not be as important. Plug some numbers into a ballistics program and see how much the differences you experience will effect you enough to care. For a .308 this may only effect your kill range by 20 yards. Since windage is tighter than elevation on a center mass shot you may be able to disregard the pressure.
On a side note i can't stabilize 75gr .224 bullets in my 1-9" twist barrel but others can. This is due to the fact that i am shooting a marginally stabilized bullet close to see level while others are at altitude where the bullet is stabilize due to lower pressures. Something to keep in mind when shooting heavy for caliber loads.
Just know your equipment and it's limitations. Good luck on your deployment and good hunting.
I think the bigger question here is wether the difference in pressures you will be seeing is enough to change your poi such that it changes your effective range.
Higher pressure will slow the bullet faster therefore lower your poi and increase flight time allowing wind to have a larger effect on the bullets trajectory.
For target shooting this is important because you reach the transonic zone sooner and the bullet will tumble but when you are looking at effect kill ranges as a sniper the effect may not be as important. Plug some numbers into a ballistics program and see how much the differences you experience will effect you enough to care. For a .308 this may only effect your kill range by 20 yards. Since windage is tighter than elevation on a center mass shot you may be able to disregard the pressure.
On a side note i can't stabilize 75gr .224 bullets in my 1-9" twist barrel but others can. This is due to the fact that i am shooting a marginally stabilized bullet close to see level while others are at altitude where the bullet is stabilize due to lower pressures. Something to keep in mind when shooting heavy for caliber loads.
Just know your equipment and it's limitations. Good luck on your deployment and good hunting.
Re: Barrometric pressure
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Winter_Shooter</div><div class="ubbcode-body">
This sounds wrong to me.... I always thought higher humidity meant more air resistance, thus requiered more elevation to hit the target...
</div></div>
It does sound strange, but the calculations in chemistry explain it: each particle (molecule) in a gas basically claims the same amount of space, water (H2O) weighs 18 atomic mass units (AMU), the main components of air: O2 is 32AMU and nitrogen N2 is 28 AMU since the water particles are lighter they reduce the density of the air
if water is in the liquid state (fog/rain) it greatly increases the air density, but you cannot see any distance anyway so that is an issue for artillery not rifle shooting
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Winter_Shooter</div><div class="ubbcode-body">
This sounds wrong to me.... I always thought higher humidity meant more air resistance, thus requiered more elevation to hit the target...
</div></div>
It does sound strange, but the calculations in chemistry explain it: each particle (molecule) in a gas basically claims the same amount of space, water (H2O) weighs 18 atomic mass units (AMU), the main components of air: O2 is 32AMU and nitrogen N2 is 28 AMU since the water particles are lighter they reduce the density of the air
if water is in the liquid state (fog/rain) it greatly increases the air density, but you cannot see any distance anyway so that is an issue for artillery not rifle shooting
A
Augustus
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Re: Barrometric pressure
Get a ballistic calculator and play with. Atrag loaded with Lapua inputs shows .7 mil difference in drop at 2000 yds with a 1 in. HG change. That amounts to about 50 inches. I would think your boss would need to know this if he is going to be in charge of taking and losing lives.
This sort of incompetence drives me nuts.
Get a ballistic calculator and play with. Atrag loaded with Lapua inputs shows .7 mil difference in drop at 2000 yds with a 1 in. HG change. That amounts to about 50 inches. I would think your boss would need to know this if he is going to be in charge of taking and losing lives.
This sort of incompetence drives me nuts.
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