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If I sight my scope at 3000ft for a 250yd zero and climb to 12,000ft what will be my new zero?

Then, if at 12,00ft I readjust for the original 250yd zero, what will my new drop at 550yds be, given that the 250yd zero at 3,000ft gave me a 47" drop?

Load is 7mm Hunting VLD at 2,780fps.

Thank you for your help.

Alvaro


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It's not the altitude per se, it's the barometric pressure you need to factor in:

http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html


Use the table provided in the link and you can figure out your drops with any ballistics program.



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If I sight my scope in a barometric pressure environment of 26.8 inches of mercury, and climb until I reach a place with a barometric pressure of 18.9 inches of mercury, what will be my new zero?

Then, if at 18.9 inches of mercury I readjust for the original 250yd zero, what will my new drop at 550yds be, given that the 250yd zero with 26.8 inches of mercury gave me a 47" drop?

Load is 7mm Hunting VLD at 2,780fps.

Thank you for your help.

Alvaro

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The quicktarget that comes with Quickload can account for altitude, but I find that drop charts are not near as good as getting to the hunting area weeks early for scouting and target practice. I put glow tape on the turret and marked on it at the elevation and range I will hunt.

That was my personal long range breakthrough in 2013. No calculations, no drop charts, mark the turret based on reality.


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A wise thing to do, clarkm, if I could, but this will be in the Tien Shan Mountains in Central Asia and I will just go there for the hunt.
There is no way I can go now, climb to 12,000ft and adjust the turret, return home, and go back to Kyrgystan back for the hunt next month.
Alvaro

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Run the numbers. Typically the factors don't really mean a miss until you start getting past 600 yards. Beyond that you need to start having some sort of ability to measure barometric conditions. It Becomes a really big deal at 800 and beyond. Just guessing without looking I bet your 250 yard zero would not change much.

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Originally Posted by BBerg
Then, if at 18.9 inches of mercury I readjust for the original 250yd zero, what will my new drop at 550yds be, given that the 250yd zero with 26.8 inches of mercury gave me a 47" drop?

Load is 7mm Hunting VLD at 2,780fps.

Thank you for your help.

Alvaro


If you're contemplating a 500 yard shot, you really need to develop the capability to figure this out for yourself.

Or to put it another way, you shouldn't rely on someone else to figure it out for you. Especially on the internet.

Go to this link (Berger ballistics calculator) and input your numbers. You don't need barometric pressure, just altitude. Then check to see if this model holds true for your locale:

http://www.bergerbullets.com/ballistics/



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Given a 250 yard zero:

Drop at 500 yards

At 26.8 inHg = 29"
At 18.8 inHg = 27"


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Dogshooter,

A 250yd zero at 3,000ft -> 29" drop @ 500yds
A 250yd zero at 12,000ft -> 27" drop @ 500 yds...

OK

But what does the 250yd zero at 3,000ft transform into when you take your gun to 12,000ft??

That is the question...

Thank you!

Alvaro

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12,000' IS 18.8 inHp

Barometric pressure and altitude in ASL (average) are the same thing.

At 3000' (26.6 inHg) 250 yard = +2.3" @ 100 yds
At 12000' (18.8 inHg) 250 yard zero = +2.2" @ 100 yds

So, if you make no changes, assuming your rifle stays zeroed on the 10000 miles worth of flights.... the difference is about 2-3" less drop at 18.8 inHg than at 26.6" inHg.... meaning not enough to matter.



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Originally Posted by BBerg
Dogshooter,

A 250yd zero at 3,000ft -> 29" drop @ 500yds
A 250yd zero at 12,000ft -> 27" drop @ 500 yds...

OK

But what does the 250yd zero at 3,000ft transform into when you take your gun to 12,000ft??

That is the question...

Thank you!

Alvaro

Any difference will be in fractions of an inch.

Most any ballistics calculator will give you "specifics", although they are really still just educated estimates


One shot, one kill........ It saves a lot of ammo!
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Originally Posted by smokepole


If you're contemplating a 500 yard shot, you really need to develop the capability to figure this out for yourself.

Or to put it another way, you shouldn't rely on someone else to figure it out for you.

...




Sometimes you just have to try for a long shot, and for this reason I practice and practice and practice, and I am shooting my 7x65R K95 kipplauf twice every week from field positions. This is Friday's attempt at 550yds, lying over my pack (1" grid):
[Linked Image]

I would have guessed I am developing my capabilities correctly and that there was nothing wrong seeking for technical advise here, as there are very knowledgeable posters willing to help...

I prefer to get close as for me the challenge a difficult approach offers is more interesting than an aseptic 700yd shot. But this is just my personal preference and I fully respect others' preferences.

As an example, this photo is from where we spotted my Blue Sheep. I was hunting in the Himalayas, in Nepal:
[Linked Image]

I could have put it down with a 700yd shot, I think, but I'd rather try getting closer and making it more "personal". So we were on the move
[Linked Image]

We went over a saddle at 16,400ft:
[Linked Image]

And, finally, almost too late into the day, and too far from my tent, I could take my shot at 250. With this result.
[Linked Image]


At 55, I can't cope very well with anybody telling me what I should or should not do, but let us leave it there.

Alvaro


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Alvaro,

thank you for the great pictures of the mountains. Talk to you soon.

C.


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Badass hunt! I can't think of a more perfect location for a "watch"! Great sheep and unique beautiful country. You're a lucky man.


Originally Posted by Bristoe
The people wringing their hands over Trump's rhetoric don't know what time it is in America.
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Super cool hunt, can't wait to see pics of the next one. I hope I can climb like that when I'm 55....

Best of luck on the up coming hunt.... I'm pretty sure that kind of shooting will get it done. Nice to see someone taking their hunting marksmanship seariously from field positions.

Out of curiosity, have you hunted Barbary/Aoudad?


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Originally Posted by BBerg
I would have guessed I am developing my capabilities correctly and that there was nothing wrong seeking for technical advise here, as there are very knowledgeable posters willing to help...


Yes, I seek technical advice here too. But I think asking someone else to calculate where your bullet will impact at 550 yards is going beyond "technical advice."

I wish you good luck on your hunt. If it were me, I would not trust someone else's answer on where my bullet would impact at long distance, unless I could independently verify it myself.

Because if you get a 550 yard shot, knowing where your bullet will impact is 100% your responsibility.



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Originally Posted by smokepole
Originally Posted by BBerg
I would have guessed I am developing my capabilities correctly and that there was nothing wrong seeking for technical advise here, as there are very knowledgeable posters willing to help...


Yes, I seek technical advice here too. But I think asking someone else to calculate where your bullet will impact at 550 yards is going beyond "technical advice."

I wish you good luck on your hunt. If it were me, I would not trust someone else's answer on where my bullet would impact at long distance, unless I could independently verify it myself.

Because if you get a 550 yard shot, knowing where your bullet will impact is 100% your responsibility.



+1


smile


Originally Posted by Bristoe
The people wringing their hands over Trump's rhetoric don't know what time it is in America.
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Originally Posted by smokepole
...I think asking someone else to calculate where your bullet will impact at 550 yards... ...unless I could independently verify it myself.


smokepole,

I am not asking.. uuhh! where will my bullet impact at 550yds? like I was stupid... I shoot quite a bit, as I said, and I know quite well the real trajectory of my gun and load up to 550yds (500m) which is the distance I regularly shoot at for practice.

See another target from another day.. On this occasion it was 440yds (400m), as I check the adjustments in my ballistic turret every 100 meters, not trusting published bcs or any software's prediction. The red bull is 2" diameter.
[Linked Image]

But I also do quite a bit of hunting to practice my shooting, like my yearly trips either to Namibia or to RSA, or to both countries in the same year, to do culling. These photos are from this year's trip. I took my 6XC barrel loaded with 90gr Accubonds, 105gr Hunting VLDs and A-Maxes.

This big baboon fell to an A-Max at 563yds, when the poor bastard thought he was safe:
[Linked Image]

Here is the result of a morning sprinbok cull hunt. In the day I killed 26 with 27 bullets, from 330 to 566 yards:
[Linked Image]

So yeah, basically I can say that I know where should my bullet hit...

What I am asking is for an indication of what does the book say on how will altitude affect my trajectory...

I have hunted seven times above 11-12,000ft in the Pamir, Tien Shans and Himalayas, and when I have test shot the gun before starting the hunt I have always noted the bullet would print slightly high. Not as much as to touch the scope, but I always had the idea of dialing 1 to 3 or maybe four clicks less depending of the distance, should a long shot present itself...

In October you can find me in the Tien Shans, in November in the Alps, and in March in the Himalayas for my second hunt there.

Here you can see one of the Alpine Chamois from last year... http://www.youtube.com/watch?v=38ksXxy5cdk&feature=youtu.be Same gun, 6.5x57R barrel loade with 140gr A-Maxes.

Best regards,

Alvaro

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Originally Posted by BBerg


smokepole,

I am not asking.. uuhh! where will my bullet impact at 550yds? like I was stupid... I shoot quite a bit, as I said, and I know quite well the real trajectory of my gun and load up to 550yds (500m) which is the distance I regularly shoot at for practice.



Well, my apologies then. It sounded to me like that was what you were asking:


Originally Posted by BBerg
Then, if at 12,00ft I readjust for the original 250yd zero, what will my new drop at 550yds be......?



Originally Posted by BBerg
Then, if at 18.9 inches of mercury I readjust for the original 250yd zero, what will my new drop at 550yds be.......?







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Maybe I did not express it properly, or maybe you do not want to understand it and not having anything else to do you are trying to have fun on me, or maybe you are just a [bleep], but I did not ask where will my bullets land at 500 meters.
I asked that given a well known point of impact at 500 meters what will the effect of a 9000ft climb will be.
Which is something different.
Do not bother to reply as I will put you on my ignore list and never read anything that comes from you.

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