CDS dial vs. other dial?

[Wetwoodshunter]

So,

I was invited by a friend who lives in Montana to go elk hunting with him this year, he told me that the majority of his free time will be during rifle season.

I have a Leupold Vx-2 3x9 50mm obj. That is on a completely custom 7mm rem mag. rem 700 rifle that I am going to take with me to Montana this year, if I draw an "Combo A" tag. I am hoping to get this gun set up so that I can take shots at elk comfortably at 600 yards.

Anyone out there using a CDS dial on their gun? I was wondering how easy, or is it necessary to switch dials if the elevation changes a ton. Where I normally hunt with a rifle I am at sea level but when I go to Montana I think that the elevation is going to be closer to 4,000-5,000 ft. What would be the best way for me to set the scope I already have up?

My current load is a 160gr. sierra game king SBT at 2855 fps, sea level. I'm also working up a load right now with Nosler LR Accubonds, hoping to get the accuracy that I can get out of the game kings, but have not gotten them to group as well.

[jackelope]

So,

I was invited by a friend who lives in Montana to go elk hunting with him this year, he told me that the majority of his free time will be during rifle season.

I have a Leupold Vx-2 3x9 50mm obj. That is on a completely custom 7mm rem mag. rem 700 rifle that I am going to take with me to Montana this year, if I draw an "Combo A" tag. I am hoping to get this gun set up so that I can take shots at elk comfortably at 600 yards.

Anyone out there using a CDS dial on their gun? I was wondering how easy, or is it necessary to switch dials if the elevation changes a ton. Where I normally hunt with a rifle I am at sea level but when I go to Montana I think that the elevation is going to be closer to 4,000-5,000 ft. What would be the best way for me to set the scope I already have up?

My current load is a 160gr. sierra game king SBT at 2855 fps, sea level. I'm also working up a load right now with Nosler LR Accubonds, hoping to get the accuracy that I can get out of the game kings, but have not gotten them to group as well.

Amateur hour here but I think I have this pretty well figured out.
The CDS dials a specific range. That will change at elevation.
The M1 turret is an option where I'm pretty sure you won't have to change the turrets, you dial the drop...so using your ballistic software, you can dial the drop ... IE a bullet drops 10" at sea level but drops 15" at 5k' so just dial for the 15" drop rather than 10". You just have to know the differences in trajectory at different elevation.

[jackelope]

500'




5000'

[bobcat]

Going by the data that Jackelope posted, at 500 yards there's only 2 inches difference in drop between the 500 feet in elevation versus the 5,000 feet. At 600 yards only 3 1/2 inches. Since you're elk hunting, a couple inches isn't that significant. You might be just fine with the dial you already have.

[ipkus]

The CDS is good to a point.

I took the ballistics for my gun (300 WM) and and made a spreadsheet showing differences in temperature from 20 to 50 F and elevation from 2,500 to 10,000 ft.

From that data I had a CDS made using 50 F and 5,000 ft.  At 500 yds. it is only off 2" one extreme or the other.  At 600 yds. it's double that, and one should keep that in mind if shooting that far on with extreme variables.

[Stein]

I range my gun here at pretty much sea level and hunt at about 4,500.  I split the difference and printed a dial for about 2,500' that I use everywhere.  As others noted, you are talking about an inch or two max.

[Wetwoodshunter]

Great info and thanks guys. I like the idea of what you did Stein that sounds like a logical way to get around the altitude problem.

[kentrek]

Going by the data that Jackelope posted, at 500 yards there's only 2 inches difference in drop between the 500 feet in elevation versus the 5,000 feet. At 600 yards only 3 1/2 inches. Since you're elk hunting, a couple inches isn't that significant. You might be just fine with the dial you already have.

3 inches of error doesn't seem like much but for me it's too much

This will be different for every person but look at it this way....I've watched my heart racing bounce cross hairs up to 6 inches before on animals...add that error to the 3 inch elevation error and now we're at 9 inches of error...now that could work in your favor to give you an end result of only 3 inches of error...now that's just one way vertical..with only an elevation & hold error...add the other factors such as the wind or how accurate your rifle is and it's a missed animal or worse a wounded one

Long winded but my point is that in a miss all the error adds up one factor at a time

[kentrek]

My advice is keep your cap totally free of obligations, use a specific printed chart for stuff in the 400 yard range but use your phone for the longer stuff...if you don't have time to use a shooting application then you probably shouldn't be shooting it any how

And most definitely take extra bullets and practice while on your hunting trip...confidence is everything

[jackelope]

Going by the data that Jackelope posted, at 500 yards there's only 2 inches difference in drop between the 500 feet in elevation versus the 5,000 feet. At 600 yards only 3 1/2 inches. Since you're elk hunting, a couple inches isn't that significant. You might be just fine with the dial you already have.

3 inches of error doesn't seem like much but for me it's too much

This will be different for every person but look at it this way....I've watched my heart racing bounce cross hairs up to 6 inches before on animals...add that error to the 3 inch elevation error and now we're at 9 inches of error...now that could work in your favor to give you an end result of only 3 inches of error...now that's just one way vertical..with only an elevation & hold error...add the other factors such as the wind or how accurate your rifle is and it's a missed animal or worse a wounded one

Long winded but my point is that in a miss all the error adds up one factor at a time

Based on your logic, you're shooting rifles that hold sub 1/2" groups?

[jackelope]

My advice is keep your cap totally free of obligations, use a specific printed chart for stuff in the 400 yard range but use your phone for the longer stuff...if you don't have time to use a shooting application then you probably shouldn't be shooting it any how

And most definitely take extra bullets and practice while on your hunting trip...confidence is everything

Do these app's work where there is no internet service?

[Stein]

My advice is keep your cap totally free of obligations, use a specific printed chart for stuff in the 400 yard range but use your phone for the longer stuff...if you don't have time to use a shooting application then you probably shouldn't be shooting it any how

And most definitely take extra bullets and practice while on your hunting trip...confidence is everything

Do these app's work where there is no internet service?

Yes, although you won't get real time met data.


Sent from my iPhone using Tapatalk

[kentrek]

Yeah no service is required for the shooting apps..and yes we're typically shooting pretty accurate rifles

[BULLBLASTER]

I get different numbers using my calculator on my phone. This is with 160 Sierra Spbt bullet at 2855 changing only pressure. From 29.9 to 24.5 (close for 5500 elevation)
I get 1 moa difference. Now add temp changes to that and it could grow or shrink.
Warmer air has less drop than colder air, thinner (higher elevations and less pressure) has less drop than more dense air.

I use moa dials on my rifles, all but one that I had a turret built and lost the moa dial.
I much prefer using pressure instead of elevation and a moa dial.
 

[jasnt]

"I use moa dials on my rifles, all but one that I had a turret built and lost the moa dial.
I much prefer using pressure instead of elevation and a moa dial.
 "