Ballistic calculator conceptual difficulties.

[Texashark]

I'm not sure this is the right place, but I'll ask anyway.
I'm having trouble wrapping my mind around a zeroing issue.
I have a 1000 yd zero on my .416 at 300 ft altitude .

How will I show what the impact point would be at 6685 Elevation at 1000 yds with this zero?

If I simply change the elevation in the calculator it will assume a zero at 1000, but my clicks will obviously be different to get to 1000 at the different elevations.

Will I have to get a zero at 6685 to calculate this, or is there a way to manipulate this.
I use Patagonia cold bore and JBM.
Thanks, Dave

 

[ShtrRdy]

Are you trying to solve a real problem?

 

[Timo Turl]

That’s why we zero at 100 yards. Your zero won’t change at 100 yards due to environmental factors.

 

[Texashark]

Yes, I have a .416 Barrett that I am going to shoot at the King of 2 Miles in Raton.
I have 80 MOA worth of scope mount and rings, and my rifle will not zero at less than 1000.
In fact, i am bottomed out on the scope at 1000 and still .2 mil high in the scope..

Regardless, I can zero @ 5 mil high at 300, but my altitude is 385 feet here, and Raton is 6675.
I may or may not have a chance to get a good 1000 yd zero at Raton.

I am trying to determine if there is a way to use the 1000 yd zero i have to predict the 1000 yd zero at Raton altitude, without introducing the 700 yds of variable to the actual 1000 yd zero

 

[_Windrider_]

With a 100 yd zero atmospherics are inconsequential. With a 1000 ya zero they are critical. You can zero for 1k where you live and recorded the atmospherics. When you get to ration, you will need to adjust your zero.

What program are you using?

 

[Mordamer]

With some calculators you can set your zero distance to 100 yards and set a zero offset. Strelok allows this and I though AB had a zero offset as well. If you have this option, I believe it would fix your problem. Just set your zero distance to 100 and plug in your zero offset. That won't change with environmental.

Your 1000 yard zero will change day to day even at the same shooting range because of pressure and temperature differences.

 

[THEIS]

Hi,

Sorta Off Topic but just in case it could be helpful to other members...
Texashark is a life long knowledge database of everything BMG. He has been in the BMG game for a very long time and knows it in and out.

Sincerely,
Theis

 

[Texashark]

I'm using JBM and Patagonia Cold Bore.
Both of them are right there together and offer zero offset.

Maybe I'm overthinking this and just need to use a 300yd zero with the offset if I can't get a true 1000 yd zero before I shoot.

Theis, thanks for the kind words, but I'm reminded how little I actually know every time I shoot the BMG.

 

[_Windrider_]

I'm using JBM and Patagonia Cold Bore.
Both of them are right there together and offer zero offset.

Maybe I'm overthinking this and just need to use a 300yd zero with the offset if I can't get a true 1000 yd zero before I shoot.

Theis, thanks for the kind words, but I'm reminded how little I actually know every time I shoot the BMG.

So I just used some BS stuff in Ballistic AE which uses JBM engine. I made up a 1k zero and some atmospherics and made up some Bs current atmospherics. You can see it accounts for the difference and says you have to dial .7 at 1k in current conditions

 

[ShtrRdy]

Using JBM Ballistics there's a way to read off the angle, ( milliradian ), for a given set of conditions. You could simulate the case at your home Altitude, make note of the angle, then set up a simulation for Raton and note the angle. The difference of the two angles should be what you'll need to adjust.

 

[LastShot300]

I'm using JBM and Patagonia Cold Bore.
Both of them are right there together and offer zero offset.

Maybe I'm overthinking this and just need to use a 300yd zero with the offset if I can't get a true 1000 yd zero before I shoot.

Theis, thanks for the kind words, but I'm reminded how little I actually know every time I shoot the BMG.

In CB check the DROP (not PATH) to account for the absolute differences between the two scenarios.

 

[Long Range 338]

Do you have enough reticle above the crosshairs to use as a 100 yard zero? Maybe not the best solution but possibly the easiest without having to rezero.

 

[Texashark]

Do you have enough reticle above the crosshairs to use as a 100 yard zero? Maybe not the best solution but possibly the easiest without having to rezero.

Yes, I zero 5 MIL Low in the reticle at 200 - 300 yds, works out about the same.

 

[PracticalTactical]

I would suggest that you make a second profile with a fake 100 yard zero that correlates to your 1000 yard zero.

This would create a static base line value that is for the most part free of atmospheric influence.

I would get a large target and put an aiming dot at the bottom of it, then shoot at that dot from 100 yards with your 1000 yard zero and measure the impact distance from where you aimed.

Convert that to MOA or MILs or whatever unit you work in and tweak your settings to match all other values to match between both profiles, except use the 100 yard zero on the new profile.

Then subtract your MOA offset from the drops provided.

You could then compare the two models to confirm the result is what you are expecting.

A word of caution here though... At close range the sight height above the bore will have a greater influence on your data than you might expect. So I would not change the scope height in your 100 yard model, I would just incorporate the needed MOA offset to balance it out... If you need to.

 

[Nik H]

In CB check the DROP (not PATH) to account for the absolute differences between the two scenarios.

^This