HNDLDR
Well-Known Member
I don't have a ballistic calculator. Of our deer rifles are sight in at 5328 FT elevation is there a way to calculate their trajectory at just over 10,000 FT?
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Altitude change on trajectory??
- Thread starter HNDLDR
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Try using Berger's or this site's ballistic calc.
HNDLDR
Well-Known Member
I guess what's confusing me is if a particular rifle is sighted as on at 200 yards at 5328 ft, it wouldn't be on at 200 yards at 10,000 ft. Correct? How is the best way to calculate a drops at 10,000 ft with a zeroed rifle from 5328 ft. Could I calculate drops at 5328 and 10,000 with the zero range at 0 yards and find the difference at 200 yards? Then just dial in the difference when I get to 10,000 feet elevation and use a drop chart for 200 yard zero at 10,000 feet? I hope this is making sense. Please excuse my ignorance and confusion.
To develop your drop chart, there are info you need, like bullet weight, BC, velocity, sight height, etc ...
Like Feenix said, you just need to use ballistics software. For example, "Shooter" is an app you can download to your smartphone and you input all of the environmental parameters for your load... including the 5328 altitude (I prefer absolute pressure), temperature, zero distance (200 yards in your case) as well as your muzzle velocity and ballistic coefficient. All these inputs are specific to where you sighted in your rifle.
Then there is a totally different window that you enter the environmental parameters for the shot you want to take while you're hunting (temperature, humidity, altitude (or absolute pressure) and shot angle. It uses your load information from the previous window to calculate everything for you including the very small difference in 200 yard zero.
You can either use your smart phone in the field while you hunt, or just use the data at home to create a trajectory table that you'll print out and bring with you. I usually do both... the printed out trajectory table obviously estimates the altitude/pressure that you'll be shooting, and is fine out to medium range shots. For true long range shots you'll need the smart phone with you so that the environmental parameters are exact for right where you are shooting from.
If you don't have a smartphone, there are plenty of online computer based options that do the same exact thing.
Does that make sense?
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HNDLDR
Well-Known Member
I only have my IPhone at my disposal and it won't let me use the G7 calculator, but on Nikons calculator there's only one click difference for a 1/8th minute scope at 200 yards between the two elevations using the numbers for a 7mm 140 Nosler balistic tip with a muzzle velocity of 2743 (wife's 7mm-08). Perhaps I'm over thinking this for shots out to 500 yards or so. I just used standard barrametric pressures for those altitudes.
HNDLDR
Well-Known Member
Thanks Timber338 that's exactly what I was looking for.
I think you're right on track for wanting to know your exact trajectory, we are always striving for perfection. Aim small miss small.
HNDLDR
Well-Known Member
I agree. I haven't been able to verify the BC's on those Noslers so I don't know exactly how over inflated the published ones are. Just trying to get as close as possible.
Laelkhunter
Well-Known Member
I think there is much confusion when trying to think these things out, especially by me.
When you say there is only 1/8th minute difference, you might be correct, however:
Let's say you run the program for your rifle when sighted at the range at your house, and there is a 1/8th minute difference from when you THEN run the same info, but add the higher altitude.
Say for instance, I enter all relevent data for New Orleans (sea level), and get the drop info out to 500 yards. Then I run the same info for 8000 ft altitude, the drop at the different distances might vary only an inch or two. But, If I run the program of sight-in at sea level, how can I input the altitude of 8000 ft for actual hunting conditions?
The program does not have the info (altitude,etc) of where you ORIGINALLY sighted it in, then shot it later at the higher altitude. It is being given TWO different sets of numbers.
What we need, and it might be available is a program that you enter all info into, including the altitude where the rifle was originally sighted in, THEN add the altitude that you will be hunting at. It should make a difference, right?
Did I cause mass confusion here, or am I just totally off-base?
HNDLDR
Well-Known Member
You're exactly right. From what I'm understanding from Timber 338, the Shooter ballistics App for a smart phone will let you enter your original sight in information and it will calculate where your bullets will hit at a different elevation. I have not verified this yet as I have to check with my wife before I spent the $9.99, or whatever it is, to purchase the App. (Sad I know)
bigngreen
Well-Known Member
The altitude change your talking with a 200 yard zero changes it zero, if your 300+ yard zero then you'd start having issues but as it is just change your setting to expected elevation and you'll be running close. Best is using most apps is to input the sight in conditions when saving the bullet data then that will be taken into account from there on out.
CB11WYO
Well-Known Member
For what it's worth, the Strelok App lets you input the original sight-in conditions as well as the current conditions you are in.
If you live at 1000' and sighted in at 70* F you record that in the app under "sight-in" conditions. Then when you get to 10,000' to hunt at 40* you input that for "current" conditions and it will give you the ballistic solution AS IS RELEVANT TO YOUR ZEROING CONDITIONS. (just make sure the "Sight-in Conditions Considering" box is checked)
Strelok was free for my Android phone, I think it's available for iphones, but it might be a paid app.
Laelkhunter
Well-Known Member
Thanks for the info. That sounds like exactly what I need.
