Altitude effect on custom dial scope

[Schreds]

I have purchased a Leupold 3i 3.5-10x40 CDS-ZL scope. I purchased this scope with the intent of putting it on my .300 Win Mag TC Compass which I use for elk hunting. I'm shooting 180 grain Nosler Accubonds. I have yet to send in for my custom dial and this is where my question lies. Part of the information they request in order to build the dial is altitude and temperature. I hunt in Wyoming at about 8500- 9500 feet. I live in Kansas at about 1500 feet. Obviously this is where I do all of my practicing and where I will set my zero. My question is, how much will the difference in elevation affect the accuracy of the scope/dial? I'm anticipating a maximum range of around 600 yards as this is about all I have room to practice. I'm also not shooting competition, just trying to put one in the power plant of an elk. Thanks for any input.
Schreds

 

[Sockeye66]

Try an online ballistic calculator like Hornady or Vortex and plug the numbers in. I'm guessing out to 400 will be a few inches and at 600 around 6in. You could split the difference on the custom dial and set it at 4500 and it only be a few inches either way.

 

[Koda_]

Thats a pretty large difference, if I recall there is a tolerance of about +/- 2000ft elevation. You could split the difference if you can live with a few inches either way but that sounds complicated estimating and kinda defeats the purpose of having the custom dial.
What I would do is get your free dial for exactly where you hunt, then pay for a second one for where you live and target shoot at. The extra cost is minor compared to the price of the hunt. Or just skip the home elevation turret all together, the turret always goes back to zero and a click is still 1/4moa, you probably should re-zero at your hunting environment anyways with that kind of elevation difference.

 

[Rick Richard]

600yards max? Won't make a "hill of beans" difference between those two variances in altitude.

 

[BigNate]

Put your specific data in an app and compare the differences.
You might just have different range cards, one for altitude and one for practice. They likely won't be very different up to 500 yards.
Get the dial for hunting, you won't be thinking clearly enough to make corrections under pressure. At home you'll have plenty of time to make calculated adjustments.
Just my $.02 worth.

 

[med358-boise]

About 6 inches at 600. I have about 4 CDS scopes and have not sent in for single dial. What if you change bullets? What if you change powders? What if you decide to move the scope to a different rifle? What if your next hunt is at 5000 ft?

You are going to much better off learning to use a ballistic calculator and making a stock chart for your specific hunt.

 

[Frank in the Laurels]

..your target area is as big as a beachball...hardly think a couple of inches will make much difference overall....unless your one of those claimed eye socket shooters at 1000 yds found here...enjoy your hunt !

 

[JAYgs8163]

Any simple ballistic calculator will tell you this.

 

[Shane Lindsey]

But, if you are half a beach ball off in your aimpoint, range estimation, stable rest, temperature, etc., you are now cutting into that margin of error even more. The goal is not to just get it enough. The goal is to put it exactly where you aim. (I am in the camp of not using pre-cut turrets either), but do what is most confident for your style of shooting.

The old rule before all the calculators and ballistic apps was to add or drop 1 MOA for every 20 degree temp change and add or drop 1 MOA for every 5000 feet climbed (I think, it has been awhile). This was with a 308 win, but you can play with a calculator and get a good idea what your rifle/load needs. Try to zero at your hunting location if possible, but may not get to the exact altitude based on your basecamp, but will be surely closer than home.

You could print a few from JBM with varying ranges of 2500 feet or so. Or get the free .$99 app and plug in the numbers once you actually get on site as they change from different positions/conditions.

Good luck on your hunt!

 

[Jeffrey Van Zandt]

I have purchased a Leupold 3i 3.5-10x40 CDS-ZL scope. I purchased this scope with the intent of putting it on my .300 Win Mag TC Compass which I use for elk hunting. I'm shooting 180 grain Nosler Accubonds. I have yet to send in for my custom dial and this is where my question lies. Part of the information they request in order to build the dial is altitude and temperature. I hunt in Wyoming at about 8500- 9500 feet. I live in Kansas at about 1500 feet. Obviously this is where I do all of my practicing and where I will set my zero. My question is, how much will the difference in elevation affect the accuracy of the scope/dial? I'm anticipating a maximum range of around 600 yards as this is about all I have room to practice. I'm also not shooting competition, just trying to put one in the power plant of an elk. Thanks for any input.
Schreds

you are better of dialing it your self get a Kestrel 5700 (DA) is what you need a range then dial it

 

[landonm]

If you want the best of both worlds (keep the ballistic turret for quick shots, and still have perfect solutions regardless of elevation and temperature changes), take a look at the Revic BR4 Ballistic Rangefinder. It's made by Gunwerks. There's a "shoot to range" mode built in that's designed for use with ballistic turrets. Essentially, if you end up in conditions different than what your turret is built for, it will compensate based on current temperature and pressure to tell you an adjusted range to shoot for. For example, at 9500' and 30F, it might tell you to dial for 550 on your turret, although the range is 600 to compensate for the less dense air compared to what your turret was built for.
https://www.gunwerks.com/shop/ay-e1020c-revic-br4-ballistic-rangefinder-21782

 

[BrentM]

Terminal ballistics is an interesting topic. Temp and elevation play a large factor in drop. Additionally, you will need to understand slope angle affects.

Now, having a custom turret is fine if you fully understand the limits of it. I think you want to simply range, dial, and shoot. Ok, that works fine to a degree within a set of parameters and it is not ideal with slope angle. In the case of shooting at 1500 ft and 60f vs 8500 at 35f is 2.5" for my prc at 600. Nothing to worry about. If you introduce 15 degree slope you're another 2". Again, not a lot to worry about but you are now around 4" of error. If you have a moa rifle/shooter, you have 6 plus 4 or 10" of error. That's too much for me to be comfortable.

My suggestion is to get an app or go on line and dial in the ballistics. You could also ask for help here and one of us could run the numbers.

 

[orifdoc]

Using a simple ballistic app for a 180gr .308 Accubond at 3000 fps, 29.92 atmosphere, 0% RH, and 59 degrees with a 250 yard zero I get 56.2" drop and 51.9" drop at 600 yards for 2000' and 8000'. For 1000 yards it's 221.7" vs 253.4".

5" difference at 600. 32" difference at 1000.

Like others, I leave the original dial and make a range card for the elevation and predicted temperature of my hunt. If temp or humidity change, I make a mental note of it each morning. YMMV.

Most likely you'll shoot that elk at 200 yards.

 

[KsKevin]

Ran this for one of my loads (7mm Berger 168g VLD) and just altitude change from 1500' to 9000' resulted in 5" less drop. I'm guessing yiur 180g Nosler May be affected just a bit more as the BC isn't as high.

I'd suggest using a ballistics calculator to account for all the proper inputs (elev, temp, angle, etc) if/when you have a longer shot. Tape a drop chart on your stock if you want a quick and dirty reference if pressed for time on anything inside 300-400yds.