MOA at different elevations

[Turbodude]

This kind of passed my mind today thinking about CDS scopes and MOA changes at different elevations. I am located in Calif and prior to my last visit to Wyoming in 2017, sited in our rifles at about 100' above sea level at 200 yards zero. When we went to Wyoming antelope hunting at about 6000' above sea level, my partner and I both shot our bucks at 150' and 200' yards at both dead on shots. We never re-sited our rifles in when we entered Wyoming not thinking there might be an elevation difference. Honestly I have never had to change the MOA on my scope since I have owned it no matter where i have shot it. What have you guys noticed when hunting in a significant elevation change? Thx TD

 

[Colorado Cowboy]

Among hunters this has only become a topic for discussion in the last 20 years or so. It really only comes into play at extreme ranges, my guess is over 500 yards. Why did I pick this number? Because I never shoot beyond that range with my hunting rifles. I have never experienced any change that I could notice when shooting at higher elevations that I sighted my rifle at.

The extreme long range shooters do take elevation differences as part of their considerations.

I do have ballistic turrets on all my hunting rifles that have elevation as part of their basic setting. I used to live at sea level and like you I hunted at higher elevations (up to10,000' ) and I noticed no difference. The big variable for me has ALWAYS been wind!

 

[JimP]

It will make a difference but not really that much when it comes to shooting elk, deer, or antelope. Now if you were after parrie dogs at 500 yards it might.

But then it is like CC said is is mostly used by long range target shooters where a inch may be the difference between a win and a third place.

I have a ballistic program on my computer and I'll have to throw some numbers into it later this afternoon or tomorrow to see just what the difference is, but I don't worry about it where I hunt after sighting in my rifles at 6000 feet and hunting up to 10,000 feet. I don't even worry about distance either with the scopes that I have the CDS dials on. I sight in to be right on at 250 yards and then with a slight amount of Kentucky windage up or down I usually come home with my animal. I just leave the dials alone.

 

[taskswap]

I like the Strelok app, which has a little bit of a clumsy interface but I got used to it pretty quickly. I just ran the numbers for my specific load, rifle, etc. (so yours may vary). Here are a few results of interest. If you care, I shoot a 165gr 30-06 Hornady SST (0.447 G1, 2960 fps), and my scope is sighted in at 200yds with 0.25MOA adjustment per click.

At 5,500', 11 degree slope angle, 10mph crosswind at 34 degrees, 72 degrees F, 29.92inHg. Adjustment needed was -0.07MOA vertical (not even 1 click), 72 horizontal (3 clicks). This is my baseline calculation for shooting at the local range and makes sense that other than allowing for wind, I shouldn't need any adjustment (the 0.07 vertical is probably just a calculation rounding error).

Changed to 11,000' everything else the same: -0.07MOA vertical (no change), 0.81MOA horizontal (a change, but less than a click so no turret adjustment needed/possible).

Changed temp to 45 degrees (let's say it's now Rifle 1): -0.08MOA vertical, 0.92MOA horizontal (almost a fourth click, if you even want to bother).

Changed air pressure from standard to 28inHg: -0.08MOA vertical, 0.84MOA horizontal.

That's pretty informative IMO. What you can see happening is vertical bullet drop is only minimally affected by ANY of these factors - altitude, temperature, air pressure, etc. It's about 1/8" at 200yds no matter what you do. But horizontal drift from even a 10mph wind (which honestly is probably optimistic in the mountains) varied from 1.5 - 2".

A lot of the folks I talk to (and even hunt with) never take wind into account but it can be significant - probably the biggest impact of any factor. As Colorado Cowboy said above, pay attention to the wind!

But in the end, a neat feature of the Strelok app is it can show you your actual reticle with a recommended aim point on it. In all of the above cases the differences were so minimal for hold-over/hold-left for a non-adjusted turret that you could barely see that the aim point wasn't dead center. IMO, in the heat of the moment, shooting off sticks or a backpack rest, at a moving animal (even standing still, its own breathing will move its lungs measurably) at a lethal-shot target a foot or two to each side? I'd say scope turret settings are just about the smallest impact thing imaginable!

 

[mosquito]

I like the Strelok app, which has a little bit of a clumsy interface but I got used to it pretty quickly. I just ran the numbers for my specific load, rifle, etc. (so yours may vary). Here are a few results of interest. If you care, I shoot a 165gr 30-06 Hornady SST (0.447 G1, 2960 fps), and my scope is sighted in at 200yds with 0.25MOA adjustment per click.

At 5,500', 11 degree slope angle, 10mph crosswind at 34 degrees, 72 degrees F, 29.92inHg. Adjustment needed was -0.07MOA vertical (not even 1 click), 72 horizontal (3 clicks). This is my baseline calculation for shooting at the local range and makes sense that other than allowing for wind, I shouldn't need any adjustment (the 0.07 vertical is probably just a calculation rounding error).

Changed to 11,000' everything else the same: -0.07MOA vertical (no change), 0.81MOA horizontal (a change, but less than a click so no turret adjustment needed/possible).

Changed temp to 45 degrees (let's say it's now Rifle 1): -0.08MOA vertical, 0.92MOA horizontal (almost a fourth click, if you even want to bother).

Changed air pressure from standard to 28inHg: -0.08MOA vertical, 0.84MOA horizontal.

That's pretty informative IMO. What you can see happening is vertical bullet drop is only minimally affected by ANY of these factors - altitude, temperature, air pressure, etc. It's about 1/8" at 200yds no matter what you do. But horizontal drift from even a 10mph wind (which honestly is probably optimistic in the mountains) varied from 1.5 - 2".

A lot of the folks I talk to (and even hunt with) never take wind into account but it can be significant - probably the biggest impact of any factor. As Colorado Cowboy said above, pay attention to the wind!

But in the end, a neat feature of the Strelok app is it can show you your actual reticle with a recommended aim point on it. In all of the above cases the differences were so minimal for hold-over/hold-left for a non-adjusted turret that you could barely see that the aim point wasn't dead center. IMO, in the heat of the moment, shooting off sticks or a backpack rest, at a moving animal (even standing still, its own breathing will move its lungs measurably) at a lethal-shot target a foot or two to each side? I'd say scope turret settings are just about the smallest impact thing imaginable!

I used to use the strelok and switched to the hornady app both are good. They are free apps that if nothing else are fun to play with or for a learning tool( or caliber debates) . If you know your muzzle velocity they are very accurate. I only switched because i found the hornady to be a little more accurate for my rounds. Most people find its the other way around. Anyway if you don't have either on i suggest you try one there pretty cool .

 

[Bonecollector]

My buddies and I use the app, "Shooter". Very easy to use and accurate.

 

[Shane13]

Temperature differences can make a significant difference at 400+ yards as well as elevation. I use Strelok, and I keep the standard MOA dials on my scopes, rather than sending them in for custom dials for that reason.

 

[Turbodude]

None of our scopes at this time were equipped with CDS or turrets. When I had sighted my rifle in that summer it was over 100 degrees. When I killed that antelope it was 17 degrees with light snow. So that kind of goes along with what everyone here has said, really only matters at long or extreme ranges.

 

[JimP]

With that much of a temperature difference you will also get different velocities out of the same round with the higher temperature shots being a little bit faster.

There are a lot of hunters that sight in their rifles and load their ammo in the cold months and then head over to Africa in the African summer. Some very quickly learn that their loaded ammo is now shooting higher pressures than they did at home and they may experience stuck bolts along with greater recoil.

This is one place where some don't like the Weatherby calibers in Africa. Weatherby loads their rounds right up to the max pressure here in the US. Then the hunter heads over to Africa and takes a shot at a animal and at that time the tracker then needs to go find a suitable tree limb/root and a rock to get the bolt to open. While the hunter has no idea of why it kicked a lot harder and they then say that it has never done that before.

 

[taskswap]

Always a wealth of knowledge, Jim. I seriously never considered that.

 

[JimP]

My PH and outfitter asked me about my .340 Weatherby when I went to the bench to check it's zero. I just told them that I was shooting hand loads that were quite a bit under the max for that bullet and powder combination and that I had built them up in our summer here in Colorado. Granted it wasn't as hot as it could of gotten over in Africa it was in the 70's when I developed the load.

 

[Colorado Cowboy]

With that much of a temperature difference you will also get different velocities out of the same round with the higher temperature shots being a little bit faster.

There are a lot of hunters that sight in their rifles and load their ammo in the cold months and then head over to Africa in the African summer. Some very quickly learn that their loaded ammo is now shooting higher pressures than they did at home and they may experience stuck bolts along with greater recoil.

This is one place where some don't like the Weatherby calibers in Africa. Weatherby loads their rounds right up to the max pressure here in the US. Then the hunter heads over to Africa and takes a shot at a animal and at that time the tracker then needs to go find a suitable tree limb/root and a rock to get the bolt to open. While the hunter has no idea of why it kicked a lot harder and they then say that it has never done that before.

Just another reason to handload.

 

[Bonecollector]

Temperature differences can make a significant difference at 400+ yards as well as elevation. I use Strelok, and I keep the standard MOA dials on my scopes, rather than sending them in for custom dials for that reason.

Likewise.

 

[Ikeepitcold]

Among hunters this has only become a topic for discussion in the last 20 years or so. It really only comes into play at extreme ranges, my guess is over 500 yards. Why did I pick this number? Because I never shoot beyond that range with my hunting rifles. I have never experienced any change that I could notice when shooting at higher elevations that I sighted my rifle at.

The extreme long range shooters do take elevation differences as part of their considerations.

I do have ballistic turrets on all my hunting rifles that have elevation as part of their basic setting. I used to live at sea level and like you I hunted at higher elevations (up to10,000' ) and I noticed no difference. The big variable for me has ALWAYS been wind!

I agree completely