Need help with ballistics question

[Laelkhunter]

I shoot a .340 Weatherby loaded with Barnes 225 TTSX loaded to 2900 fps Bullet BC is .514 Swaro Z5 is 1.8 inches above bore line. Right now I have it shooting 1 inch high at 100 yards, 60 degree temp and 0 ' altitude

What I would like to know is when I get to 8000' at elk camp, and shoot the rifle to confirm the zero, if it is 60 degree temp, how much higher or lower will the group be?

What I am hoping to accomplish is to sight the rifle here where I live at whatever inches high or low to make it close to 2 inches high at 100 yards at 8000 feet. That way I won't have to make adjustments to bring it to where I want it., or at least have it pretty close.

I hope my question makes sense, Thanks.

Forgot to mention, my scope has BRH reticle, and I don't plan on dialing, I will be using the reticle for holdover.

 

[swampfox]

Can’t you just put your data in the ballistic app with the “zero” as your expected conditions at camp and then change the data as if you are at the home conditions and see where it says the bullet will hit at 100 yds? Not the way I would sight it in but that will give you the right data (on paper)

 

[BjornF16]

The easy solution is to zero at 100 yards ( same zero at sea level and 8,000’) and dial to whatever your desired distance is calculated for local conditions

 

[Laelkhunter]

The only thing I have is the Swaro ballistics program. I don't have any other aps (70 years old and I.T. deficient).

 

[Reburn]

IMO doing it this way is not the smartest thing you could do. However you asked how and not what we thought. I still use strelok each different app will have it in a different place

You will have to have a ballistic app to get the question. The app will need to be trued to you gun in live fire conditions to have any hope of being accurate somewhere else.

My scopes are zeroed at 100. If you are shooting at 100 this needs to be 100.




Secondly you move your zero offset to be how ever many inches high at 100. Lets say an inch. you would make zero offset +1.0

 

[Laelkhunter]

The easy solution is to zero at 100 yards ( same zero at sea level and 8,000’) and dial to whatever your MPBR is calculated for local conditions

I don't dial, I use the Swaro BRH ballistic reticle, and plan to use the reticle for holdover past 300.

 

[swampfox]

I’ve never used swaro ballistics but hornady 4dof is free and would do it. I’m sure swaro would too. I think Bjorns post is a better idea though

 

[BjornF16]

I don't dial, I use the Swaro BRH ballistic reticle, and plan to use the reticle for holdover past 300.

Then zero at 100 and calculate your holdovers for the local conditions.

 

[Shortschaf]

It will be the same zero at both elevations with that ammo

I just did it with AB app using all your inputs.

For what it's worth, I've done this exercise a dozenish times now with various calibers and the result is always the same. Zero doesn't change.

 

[Laelkhunter]

It will be the same zero at both elevations with that ammo

I just did it with AB app using all your inputs.

For what it's worth, I've done this exercise a dozenish times now with various calibers and the result is always the same. Zero doesn't change.

Perfect !! Thank you very much. Without sounding too lazy, I was hoping someone would be able to run it with the info supplied, and tell me either "It will be an inch higher" or "It will be an inch lower", or best answer I could have hoped for was yours : "No change" !! I thought with the thin air at altitude, it would be less drag on the bullet so it might shoot higher, but I guess that's why we shoot them "up there". Thanks again !

And thanks to everyone who replied, I appreciate the help, but the apps and programs are out of my area of possibilites.

 

[BjornF16]

Here is 100 yard zero at different density altitudes:

 

[BjornF16]

Unless you get/learn an app like Strelok, then your best bet in using the Swaro Ballistics program is to simply zero at 100 yards.

Swaro doesn’t allow you to enter 2” high at 100 yards (zero offset) to calculate your holdovers.

 

[Shortschaf]

Perfect !! Thank you very much

no worries. The fact that you gave every single input up front made me assume that you know the drill, and just didn't want to mess with an app ha.

Drag is certainly lower up there, but the change in time-of-flight at 100 yards only changes by 1 millisecond. So drop at short range is virtually identical.

I would still want to check zero though. For science

 

[Laelkhunter]

Unless you get/learn an app like Strelok, then your best bet in using the Swaro Ballistics program is to simply zero at 100 yards.

Swaro doesn’t allow you to enter 2” high at 100 yards (zero offset) to calculate your holdovers.

Actually it does. If you play with the "zero" figure, it will show you under the picture of the reticle, "to get a
Zero Range of 180 yards please zero your rifle with an elevation of 1 inch at a distance of 100 yards". What you can do is just change the "Zero Range" distance +10 or -10 yards, etc until you get the site in distance you want at 100 yards. Then after you enter that info, it will print a picture of the reticle with all holdovers at each reticle and their values. It also prints up the drop chart showing bullet drop out to 500 yards, along with retained velocity and energy at the given range.

 

[Laelkhunter]

no worries. The fact that you gave every single input up front made me assume that you know the drill, and just didn't want to mess with an app ha.

Drag is certainly lower up there, but the change in time-of-flight at 100 yards only changes by 1 millisecond. So drop at short range is virtually identical.

I would still want to check zero though. For science

Well, you are partially correct. I definitely didn't want to attempt the app. I have an Iphone 7, and it kicks my butt. My flip phone broke, or I would still be using it.
Without a doubt, we always shoot our rifles when we arrive at camp. Too much can go wrong and knock them off an inch or two in transit. I have been pretty lucky, and haven't had to make any changes, it just seemed the point of impact was higher or lower a little bit compared to sea level sight in, but it wasn't enough to change it.

 

[Elkbelter]

The BRH in my Z5 worked very well for me on a 388yd coyote in Colorado-7500ft--sighted in @ 200yds in NY 1300ft and just foloowed Swarovski's drop data for Colorado's elevation.

 

[BjornF16]

Actually it does. If you play with the "zero" figure, it will show you under the picture of the reticle, "to get a
Zero Range of 180 yards please zero your rifle with an elevation of 1 inch at a distance of 100 yards". What you can do is just change the "Zero Range" distance +10 or -10 yards, etc until you get the site in distance you want at 100 yards. Then after you enter that info, it will print a picture of the reticle with all holdovers at each reticle and their values. It also prints up the drop chart showing bullet drop out to 500 yards, along with retained velocity and energy at the given range.

The problem with that is when you go from Sea Level to 8,000', the 180 yard zero (from Sea Level) won't be zero at 8,000'.

However, the 1 inch high at 100 yards (at Sea Level) will still be 1 inch high at 100 yards (at 8,000').

Depending upon what your expected shot ranges are, it may not make a difference.

 

[Laelkhunter]

Exactly, that's why I posted the original question. If I could just run the program using my sea level results, then change only the altitude to 8000 feet to get my new sight in info, that would be great. But it won't compute correctly.
When I get to camp, I won't have the ability (lack of internet) to rerun the program with the 8000 feet results. I always shoot when I get up there, and if it isn't close to where it needs to be, I will make scope corrections.

 

[BjornF16]

What I am hoping to accomplish is to sight the rifle here where I live at whatever inches high or low to make it close to 2 inches high at 100 yards at 8000 feet. That way I won't have to make adjustments to bring it to where I want it., or at least have it pretty close.

If you want 2" high at 100 yards, adjust for that at sea level and it will remain the same (at 100 yards) at 8,000.

Run your ballistics before you leave home for various density altitudes that you expect to encounter (or for 8,000' DA) and you'll have your solution. It won't make too much a difference, especially on elk sized game, if you're shooting 400 yards or less.

Standard atmosphere at 8,000' is 22.22" Hg and 30.5 deg F

You can use another program like Strelok to determine what your actual zero would be at 8,000' DA with a 2" high 100 yard zero from sea level...but the Swaro program doesn't appear to do that for you.

The easy button is to simply zero at 100 yards and go from there.

 

[Laelkhunter]

...The easy button is to simply zero at 100 yards and go from there.....

Yes, that's the answer. I like easy... Thanks