Long Range 101 Part 30 - Barometric Pressure & Altitude Corrections - Rex Reviews

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Rex reviews the effects of barometric pressure and altitude on the trajectory of a bullet. In order to precisely correct for the changes in atmospheric density at different elevations, the shooter must first make an accurate determination of what the B.P. is at his location. Rex also goes over the use of cell phones for obtaining barometric data.
All the music, animations, and photography in this video were created by TiborasaurusRex, and unsigned artist.
Song Title: Particle Jam, Mine Field
Music and Lyrics by: TiborasaurusRex
Instrumentation and Vocals by: TiborasaurusRex
Recorded by: TiborasaurusRex

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16 июл 2024

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Комментарии : 128

@TiborasaurusRex 5 лет назад

Come train with Rex - in person!!! rexdefense.com/

@merlin8701 9 лет назад

Thank you so much for all of your hard work put into this video series. i have been learning a ton of good stuff!

@Dressagevids 3 года назад

I'll second that, really helpful and a huge amount of work has gone into these videos which are available for free, very generous and much appreciated

@TiborasaurusRex 11 лет назад

Glad you are enjoying the series. Thanks for watching.

@zoidelux 2 года назад

15:50 “fancy hiking guys” 😂🤣 Rex I love you 😂. Rewatching some of these videos 9 years later, still the best on RU-vid for in depth explanation. Thanks for everything you do. I still get mixed up and confused with baro pressure and DA, gotta keep refreshing my memory

@GunNtonic 11 лет назад

Rex, just wanted to say THANK YOU for sharing your wealth of knowledge. It's all starting to click and I will be much more confident shooting long range. I don't know what you do for a living but you are a incredible instructor. I have been through 30 of your video's so far, and like an awesome book, will be bummed when I get through them all. Let us know when and where we can purchase your music, love your tunes.

@TiborasaurusRex 11 лет назад

Thanks, man. I'm only half done with these videos thus far. Many more to come :-)

@JimFleming1953 10 лет назад

You do a good job of explaining why a hand held barometer is needed in the field, Rex. Thumbs up, sir!

@erikm3251 11 лет назад

Ready and waiting for Part 31, whatever it may be. Good stuff brother. I really enjoy this kind of detail. I dig the how's and why's. It got so much better when I realized you were a brother in faith. Great stuff! Thanks for the effort and time.

@TiborasaurusRex 11 лет назад

Right on. Thanks for the comments, bud.

@sorinsurrey 11 лет назад

Outstanding videos ! Barometric pressure and Altitude corrections was something taboo for me for some time , know start to make sens :). All the best for you and God bless !

@SVtgr8 11 лет назад

Rex, my method for high angle BP changes: At about 23:25 you talk about high angle shots and BP influence. At extreme angles and significant range I take absolute BP (GPS & barometer) at FFP. I then use ranging (scope or spotting scope) to calc change in ELV (vertical drop). From there ELV/BP tables to read off RELATIVE change in BP over that ELV change. Relate that relative change to my absolute reading from GPS and barometer, and thats the BP I use. I ALWAYS have my ELV/BP tables with me.

@xXxZEBRUSxXx 11 лет назад

Hey Rex, I Have been watching your video's for some time now, and I just wanna say thanks for sharing this science. Learning something new every time I come back.

@johnlee4249 7 лет назад

Great videos with outstanding info...

@TiborasaurusRex 11 лет назад

I don't use DA, the way I set up my data. Pilots use that to keep track of how much lift they have at any given moment, but for us, we won't be using that measurement.

@wmbarn123 11 лет назад

No problem, these videos are the best. You should be a teacher I have never had something broken down so well to where I can understand. Thanks man!

@TiborasaurusRex 11 лет назад

Great question. It's true that temperature and pressure are related. In chemistry, the Ideal Gas Law is expressed as a function of temperature and pressure. For our "quick charts", we will prepare a different set of data for each barometric pressure zone you may be operating in. We will then integrate the effects of both ammo temperature and ambient air temp into different columns within the B.P. data set. Our detailed ballistic calcforms will be a bit different.

@SVtgr8 11 лет назад

Rex, I am working my way through the series - great stuff. Not sure if anyone told you, but your drawings are improving as well!! ;) I will definitely share this series.

@TiborasaurusRex 11 лет назад

Thank you, sir. Glad they were helpful. Be sure to share these with your friends! Peace.

@TiborasaurusRex 11 лет назад

Thanks for the experience and insight, sir. :-) I've found my budget IR thermometer to be quite a pile as well...

@fucdagubment 11 лет назад

thanks for the great video series!

@TiborasaurusRex 11 лет назад

Atmospheric density is the best way to go if you have the tools do measure it directly as it factors in all the different drag components you will need to be concerned with. For those who don't have the tools to measure ATM density, they can use BP, humidity, and air temp to get pretty close.

@theclaymore5150 11 лет назад

Rex, thanks for the excellent instruction. I love how you throw the actual science into it. Your instructional vids have inspired this former 11bravo to start looking for the right ammo to buy a rifle for. haha

@TiborasaurusRex 11 лет назад

One way to do it is to simply average the different pressures zones to get a close estimate... If you are shooting at extreme ranges you may have to consider the shape of the trajectory to see which pressure zone the bullet will spend most of its time in. Usually, if you are shooting up-slope the bullet spends more time in the upper pressure zone than it would if shooting down-slope, due to the shape of the trajectory. Also, the drag dynamics change with velocity, so there's more to it all.

@TiborasaurusRex 11 лет назад

Its exceedingly difficult to make precise mathematical determinations of these pressure zone variations for angled shots in the field, so we are forced to use intuitive determination of that pressure value most representative of the overall trend. The human brain is actually pretty good at this, once we get a good feel of the concept.

@mrtundranutz1 11 лет назад

Good vids . Keep 'em coming .

@anthonychavez3742 6 лет назад

The Weatherflow work's great.

@TiborasaurusRex 11 лет назад

Thank you, sir.

@SmithAerosports1 11 лет назад

About to plug in and listen on my commute. Thanks in advance..

@lbcsv 11 лет назад

Love your deer graphic.

@Mrcomrie21 11 лет назад

Excellent video, love how you simplify the concepts - much of your instruction would put many of my past engineering instructors to shame, due to the sheer simplicity of your methodology. Curious, when engaging a target at a presumably much different barometric pressure, do you choose a singular barometric pressure to calculate trajectory, or do you try to plot the flight using multiple pressures at different points of the trajectory? Hope I explained my thought well enough there. Thanks!

@TiborasaurusRex 11 лет назад

Thanks, soldier.

@Mrcomrie21 11 лет назад

Dusting off my Dynamics and Fluid Dynamics books, lol, this is a terribly interesting problem to become acquainted with!

@mesevens 11 лет назад

I sent you a PM. I grew up in the Glacier Park area. Great place to be inspired and free.

@quantumfart 11 лет назад

I may not be able to shoot Extreme, or even long range just yet, but i tell ya, it sure has helped me ALOT at my work :) my dad wants to get into long range as well, i tell him to watch these vids becasue really, out of what i have found, even from reading the 23-10 and other things, you by far have a much better, more comprehensive, tutorial. but i think he likes watching people shoot deer more >.> 5+ Star/thumbs up

@TiborasaurusRex 11 лет назад

lol - I know, I'm just teasin' ya. Thanks for the offer, I may take you up on it one day :-)

@NockedUp417 11 лет назад

Yeah, I think the whole class is anxious for the next video! I was watching Marky Mark last night, but he just doesn't give the same attention to detail :)

@Mrcomrie21 11 лет назад

Ok, I now see that it's somewhat of a flight time dependent problem (gravity having more influence for longer time duration in X-pressure field). Thanks for the extra bit to ponder!

@TiborasaurusRex 11 лет назад

Most of those IR thermometers report very accurate temp readings, the difference in price is usually in construction quality and life expectancy. I am not familiar with that particular brand, but my budget IR thermometer is always out of batteries. You should be able to get one of those NAPA mechanics IR thermometers on ebay used for pretty reasonable.

@Barbarossa4U 11 лет назад

Great vid. I'd love to know the outdoor site where you got the barometer at. The best watch out there is a Casio Pathfinder PAW1500 or the new Casio Pro Trek PRW2500 which is basically the same thing. The nice thing is the barometer graph so you can see changes and trends forming and adjust quickly if needed.

@TiborasaurusRex 11 лет назад

As long as its getting its info in from the sensor, it should be more than adequate. Any unit is fine, converting pressure units won't be too hard.

@TiborasaurusRex 11 лет назад

Thank you, sir :-)

@TiborasaurusRex 11 лет назад

No problem, man. The wind video should be out very soon :-)

@jamesadams8572 6 лет назад

Thanks for all the wonderful work and your channels dedication. I can’t find your no 72 or 100 on RU-vid?

@TiborasaurusRex 11 лет назад

Howdy! I am trying to remember off hand how the instructions say to set that thing up, but yes - you will want to calibrate everything so you get your true BP and altitude values as close as possible.

@Mrcomrie21 11 лет назад

Yeah, this is another element of the problem that I see particularly difficult. I bet experience weighs in heavy on this - the piece of the puzzle I need to get out and take care of!

@TiborasaurusRex 11 лет назад

Sort of. Its very very hard to precisely account for all the pressure changes over the different legs of the bullet flightpath in the field, so we are sort of forced to expedite the process by using the pressure value most representative of the overall pressure trend at the bullets most vulnerable point in the flight path. We make that decision by looking at the trajectory curve, and then using the pressure at that point to do our calculation.

@ScottDickey 11 лет назад

Some newer phones, such as my Nexus 4, have an actual barometer in it to assist with GPS. pressureNET is one app trying to use these sensors for crowdsourcing weather information.

@masi16r 10 лет назад

How do you get the barometer reading in the Garmin GPSmap 60CSX to give you absolute or uncorrected readings? It appears that my unit is giving me altitude corrected readings because it is always in the 29-30 range no matter what elevation I have been at (4000' - 8000'). Thanks for your work! Great stuff!

@cheemsaf 11 лет назад

TRex, I thought I could've bypassed checking the pressure by just listening to the local airport's barometric pressure on my handheld radio. Thanks for correcting my assumption, as air traffic controllers & high elevation airports also correct their weather back to correlate with sea level regardless of the airport's elevation. FYI - I'm in CO, so that would have really messed my shots up.

@inuyashacoolieo 10 лет назад

i laughed pretty hard when i saw the dead dear.

@KikiRevenge 7 лет назад

Me too!

@AvocaSingleTrack 4 года назад

Hi Rex, love the videos. I plink with 300aac subsonics. The low velocity lets me practice holdovers at 100-200 yds like i'm reaching out way farther. Do I also still account for temp/air drag like you are saying here ? I keep records on my loads and i do notice the temp changing my velocity by 30-50 fps on a 1000fps load... but haven't really accounted for it yet. I stuggle to get good groups with my sub loads past 100 yds. 16" Howa bolt ... Thanks !

@TiborasaurusRex 11 лет назад

Any chronograph should work fine. I would recommended to use the cheapest one I could find at the local store. Mine is labeled: "Shooting Chrony", some generic brand, works fine - like $65 at the sporting goods store. Probably could find a cheaper one online.

@user-lo1gy8tx4c 11 лет назад

i worked in in volumetrics for around 10 years and one piece of advice i would give is dont try to save money by buying harbor freight when buying a infrared thermometer. you would have better luck buying one at a parts shop like napa then to waste money on the harbor freight ones. They might advertise that +- 4 degrees but that only last for about 30 seconds after a new batttery is installed then they get pretty worthless.

@TiborasaurusRex 11 лет назад

No problem, bud.

@TiborasaurusRex 11 лет назад

Its a Surgeon Remedy with a Schmidt & Bender PMII 5-25x56.

@hypehype1982 7 лет назад

great vids i really enjoy them. do you think a kestral 2500 will be ok for long range shooting up to 1200m? i not sure if i want to buy a 700usd unit im hoping to get with 200usd unit. do thinking the kestral 2500 will give me enough data to make difference. maybe you could do a review of kestrals?

@michaelmuzzy8401 5 лет назад

this is gold for an old 50 something guy to understand and stay up to speed.

@TheCharillz23 7 лет назад

could you point us in the direction of calculating ambient air tem and barometric pressure changes effects i am stuck on this i have reviewed these videos at least ten times to see how to correct, and i'm still stuck trying to make those first round hits

@fedeviper 8 лет назад

hi rex, im using for my correction a "smartphone" an old samsung s4 its has built in barometer, higrometer and thermometer. And integrate perfect with StrelokPro. ONLY the s4 and tab3 has it. A couple of another droid phones has barometer

@totenkopf6580 8 лет назад

Hello rex what are the formulas to compensate for barometric pressure and temperature please?

@cjurna 11 лет назад

Don't forget to "Like" the videos. I had to go back because I was anxious to get to the next video.

@TiborasaurusRex 11 лет назад

Sorry, got bogged down with some of my other studies. I've had a lot of studies on my plate this last month. Should be soon :-)

@eaglessj 11 лет назад

I received that barometer I linked you today. It looks well made and works as advertised. The only thing I didn't like is that the thermometer only reads in Celsius. Other than that, for $30 shipped you cant beat it. Anyone else interested in one, do a ebay search for 4 in 1 barometer.

@jameseves9209 11 лет назад

Hey Rex , Just got my Kestrel 4500 .... am I supposed to set the altitude reference to zero to get station pressure and just use that ... and what should i do with the sync Alt and sync Baro .... Love the series ..... God Bless

@buckshotchavez 8 лет назад

I am new to extreme Long Range shooting. am planning on getting my first rifle, questions: what do you think of the Remington model 700 long range 300 Win Mag. is the 300 rem ulta Mag better for longer Ranger. I thinking of going with the Savage Arms 112 Magnum Target 338 Lapua. I been seeing your videos and learning alot from them. Thank you for sharing your knowledge. I shoot a 50/90 Sharp's. this coming year 2016 am planning on shooting the Billy Dixon shot of 1538 Yard and out to a Mile.

@TiborasaurusRex 11 лет назад

Air density is the sum total of all the factors involved, so if the air density is the same, the trajectory should be the same. :-)

@SmithAerosports1 11 лет назад

Continued So here is what I suggest: 1. Use a topographical map or your gps to find your current altitude - write down 2. Put current altitude as reference altitude in Baro screen to get mean sea level pressure - write down. 3. Set reference altitude in Baro screen back to zero to get back to absolute pressure and getting ready to shoot. 4. Go to Altimeter screen and set reference value to mean sea level pressure that you wrote down in step 2. This way you have the right barometric pressure for

@KatsuTanda 11 лет назад

Rex, I'm trying to decide on a kestrel model to purchase. The 4000/4500 have density altitude which you don't even mention, while the 3500 will do temp and pressure without doing the calculation for DA. In your opinion, is the added DA important? Or save the money and buy other equipment/ammo?

@SmithAerosports1 11 лет назад

Continued: ...taking absolute pressure? Also, will the "DENS ALT" (DENSITY ALTITUDE) be the correct value? I need the density altitude number to plug into "Shooter" for my Droid 4. Thanks for the enlightenment . To measure the absolute pressure aka station pressure with you Kestrel 4500NV (nice choice btw) you do as you have done: you go to the Baro-screen and set Reference altitude to 0feet above sea level. When setting the reference altitude to zero you tell the Kestrel that you are at sea

@jamescolton1085 10 лет назад

Looking at the chart with the mountain picture on it I start to wonder if there is a value missing somewhere around 25.8. Perhaps that's a good reason to prefer a $20 barometer over a chart. I keep wondering if the 23-10 was written for the enemy.

@danielmazanec9393 10 лет назад

Right. I was fixing to read FM 23-10. Now, I don't think I'll even bother.

@TiborasaurusRex 10 лет назад

Daniel Mazanec The fieldcraft and tactics in the FM23-10 stand strong.

@stevenford4313 8 лет назад

I'm a commercial pilot. As such, we must consider the same factors concerning air density. It's called PRESSURE ALTITUDE

@Auntcankles 8 лет назад

+Steven Ford , I'm facinated by how much this has in common with flying. While I only fly SEL, One aspect can help you become a better "the other"(works both ways)!

@rvargues 10 лет назад

Hi Rex, What sort o spotting scope are using here it looks very compact, what power is it? really like your vids greetings from Portugal

@TiborasaurusRex 10 лет назад

This is a cheap Burris 20X... it was like $59 new. I can barely see through it anymore... time for a new one. I'll be getting in a new IOR Valdada with Mil ranging reticle very soon for review. Stay tuned!

@SmithAerosports1 11 лет назад

Continued... ...the right barometric pressure for shooting, and as long as there are no big changes in weather the altimeter screen will also show the correct altitude throughout your day. step zero would be to check that Sync baro and Sync alti are set to off, you find these settings where you punch in the reference values. [End] From question forum 02-08-2013@8:40pm LongRange Hunting Online Magazine

@SmithAerosports1 11 лет назад

Regarding Ammo temperature, how accurate must the measurement be? Will +\- 4 degrees make a significant change in bullet impact between 800-1200 yds? Im looking at a Harbor Freight IR thermometer that is accurate to +\-4 deg .

@wizardny 6 лет назад

You should have this video series transcribed into a book. You already have the illustrations.

@SmithAerosports1 11 лет назад

Kestrel setup for Absolute Pressure - From Longrange Hunting Magazine question forum 02-08-2013 @ 8:40 PM Quote: Originally Posted by bowhunthard Ok, I've just been getting my head wrapped around the idea of absolute pressure, which I need to set my "BARO" setting to "0", correct? So, I did. I then set my "ALTITUDE" setting to 29.92 inHg, right? (It calculates the altitude comprable to standard baro pressure, I guess.) So, if my Kestrel 4500 NV is set up in the previous manner, is it taki

@TiborasaurusRex 11 лет назад

Don't get me wrong, there's nothing wrong with using that measurement at all. If you set up your tables for DA, that will work very efficiently. However, many of the shooters going through this course will not be equipped to make quick DA determinations in the field, so I will show a method using more familiar inputs that are easier to determine using basic field equipment. Great commentary, sir. I may get into DA when I show how to best incorporate ballistic software devices.

@Lifebehindthearrow 11 лет назад

i notice you didnt say anything about the use of dens alt? isnt it more important to input what the bullet actually thinks its flying through conditions wise. I have found from my experince that with one wronge data point entered and everything goes bad real fast with the baro pres method. When I switched to Den Alt, first round hit % went up drastically, almost like human input error was removed, also dens is easy to fig ,if you know your temp and approx elevation. again thanks for the vid

@JColip1776 11 лет назад

I guess the galaxy note 2 had a barometric sensor built into the phone. I downloaded Symatic app called Sypressure (Barameter) and it shows your the real time pressure in hPa if you want it to read Hg you have to purchase the PRO version for 1.30. If its telling me I have a sensor on this phone does that mean it will work?

@temmenj100 11 лет назад

What chronograph do you recommend/use? Also what wind meter do u use/recommend for someone on a budget?

@ExON00 11 лет назад

I made a table showing dry air density according to pressure and temperature. I tried to calculate bullet drop using different combinations which should result in the same air density. I expected the results to be the same, but there were significant differences. What am I missing? I figured once the bullet leaves the muzzle it doesn't care what combination of pressure and temperature it is. It should be affected by air density

@michaeljordon704 4 года назад

when I look in the iOS weather app, the pressure for many different cities at many different elevations are all around 30 inHg, is the weather app wrong?

@spaghettishooter6057 11 лет назад

hey rex i was wondering what is thename of you 338 lapua rifle and the name of thescope its really cool

@jimmyforester8492 11 лет назад

That's not what I was implying. Your hunter and deer on the mountain were amazing. I just meant because you said you have a lot on your plate. Thought it might take some load off, if you had help

@masi16r 10 лет назад

Found it: Go to the Barometric Altimeter screen, click "menu" and select "Plot Ambient Pressure".

@cg4wheelinfool 11 лет назад

question... since the barometer gives you the air density and I imagine can't tell the difference between water vapor and normal gaseous components of air is there really a need to measure humidity or does the barometer give you an inaccurate air density measure because of humidity and that has to factored into it still or was humidity just an example you used?? P.S. kind of neat I thought my old chemistry professor mentioned more home runs are hit on humid days due to less air density

@unbalancedredneck5778 11 лет назад

Just one quick question, if hunting deer inside 400 meters. How far would I be off just using generic tables. I guess my main question is at what distance does it become critical to be exact?

@christyshaurette5815 6 лет назад

My Garmin measures barometer as well as ambient pressure. Which should I use?

@erichunter14 5 лет назад

CHRISTY SHAURETTE I have the same question!!??

@m4rvinmartian 5 лет назад

'Measures barometer' makes no sense. "HAS a barometer" maybe. That barometer is measuring ambient pressure, thus, a barometer.

@a55tech 9 лет назад

23-10 gives a chart in MOA but the equipment is in MRADs? The chart uses meters for range, feet for elevation, and MOA for angles lol.

@nickscape75 10 лет назад

Rex, did you ever pick up that analog barometer? if yes, could you possibly link it us in an annotation or give us the website? many thanks in advance.

@TiborasaurusRex 10 лет назад

nickscape75 Sorry, I'm still rolling with the Kestrel and my old STD ATM @ ALT charts...would still like to get one and try it out...

@bps5891 5 лет назад

Do you recall the name or website to get it?

@ImNoBSING 7 лет назад

I was surprised when I learned the newest smartphones (Samsung S7 etc.) have a very usable BUILT-IN barometer. Search for "barometer" in the app store. Give it a try! I will be using it as long as I stay within short ranges. They give you altitude too, not sure how accurate it is, probably around 0-200 meters throw.

@jobane2 9 лет назад

Rex, since you seem to correct separately for true BP and ambient temp in the calc charts, does this mean you are not a fan of the density-altitude method?

@Ahsieh2 9 лет назад

He mentions this starting around 13:30ish

@isleofgreg 9 лет назад

Obviously not

@jobane2 9 лет назад

JRR Armory At 18:45 he mentions also the density altitude as a good rough backup method, but obviously direct measurement is inherently better and more accurate and takes into account the other meteorological factors.

@wmbarn123 11 лет назад

TRex, where is your next video...the suspense is killing me!

@GroovesAndLands 11 лет назад

Why not? DA rolls all the factors affecting air density into one number.

@brianhawthorne8560 9 лет назад

I work in a field where we constantly take weather through the day usually every 15 min. to 30 min. and there is a weather kit you can buy for about 150 there is no batteries required. No tech in it required been work very accurately for wildfire fighters since the 1930. It takes wind, dry bulb temp., wet bulb temp., measures RH% and dew point. It doesn't measure barometric pressure. But still if you don't want to rely or would like a fail safe back up to tech. check it out. Forestry Supply is a good place to start.