Choosing an elevation for my Leupold CDS

Jeffpg · Dec 14, 2010

I have a new Leupold CDS scope for my Remington model 700 LSS in 300RUM. In putting together my ballistic info for the custom dial for my load, I am having trouble choosing an average elevation to set up for.

Like most of us, I hunt all over the west for multiple species and can find myself at various elevation levels, but usually 5000 to 10,000 is within the range. My Leupold Rep tells me that the range of error is about 2000' on either side...in other words if I went with my original figure of 5000', I would be good from 3000 to 7000 feet, more or less. Of course the error will increase at longer ranges, and I haven't done my homework by consulting ballistic charts as to just how much the effect will be, but I'll get around to that soon. I'm sure some of you are well schooled on these numbers, or may have a good source of information to educate me.

I feel the changes in elevation will have a minimal effect on my bullets trajectory except at longer ranges, and realize that it will fly flatter in the higher, thinner air. I also realize that having 2 different dials set up to compensate for extreme elevation changes would be best, but I want to see if I can make the one dial work across the board, even if it means learning to adjust for the extremes.

I originally intended to go with 5000' elevation and 50 degrees temperature, but I am second guessing that after talking with a few fellow hunters/shooters. I am leaning a bit more towards 7500' currently. I'm sure some of you will share opinions that will challenge my thinking on this.

My load consists of a 180 grain Swift Scirocco bullet with a .500 BC leaving the muzzle at 3250 fps.

Thanks,
Jeff

Longun · Dec 14, 2010

just sneak up and get close for a shot and you don't have to worry about all that high-tech crap......j/k

legacy · Dec 15, 2010

Wasn't Leupold offering a second set of dials for free? That would be nice because you could set the dials to different elevations, temps, etc...

Cahunter805 · Dec 15, 2010

LAST EDITED ON Dec-15-10 AT 01:06PM (MST)[p]Jeff at what elevation are you developing the load? I would probably go with 6000ft but thats just me.If you do a lot of hunting at 10000ft and over then 7500 would be good also. According to the leupold rep you would then be in the 4000-8000 range with the 6000ft turret. I suspect most of your western hunting would occur between that range. The difference in POI @ 1000 yards from 4000ft to 8000ft will be about 10" which you will just have to shoot and find out actual data and compensate. I think the cds dial is a pretty good system if the data you supply is accurate. I would recommend shooting groups out to 600-800 yards from a bench and building your own drop data.

Jeffpg · Dec 16, 2010

Yeah, I do get another dial through Leupold's current Promo deal, but I am planning to use it on a different load, using either the Nosler 200 grain Accubond or Bergers 210 grain VLD. The dials are going for about $100 each from Leupold.

The 7000' figure is looking pretty good to me right now. I am shooting at my home, which is at about 300 ft. No wonder that mountain air seems so thin to me!

Norcal300RUM · Dec 18, 2010

I have a VX3 4.5-14 at Leupold now getting a CDS dial done. I'm assuming your shooting the Remington factory load? If so, run it though a chronograph before you have your dial done. My Ultra mag shooting the exact same factory load shoots about 200 fps faster than what the load ballistic chart says. It will make a difference at the longer ranges.

Jeffpg · Dec 18, 2010

Yeah, that's a really good point and one I've been wrestling with as I had to leave home for work before I got to check the load thru the chrony.

I had actually been considering taking the chance that it would be close enough to go with just so the dial would be ready for me to try out once I got home, but since you've seen that great of a discrepancy, I believe I'll practice some patience and wait til I get back home to check it.

I have a tag for Oryx on the WSMR in February and plan to use the rifle on that hunt. I can still get it set up in time and I'll know it's right. It's not like I absolutely have to have it for the hunt anyway, as I'll also take along my Sendero of the same caliber which is set up with a Long Range VX3 6.5 - 20 x 40 with the Varmint Hunter Reticle. I zero both rifles at 300 yards anyway and the Sendero has shown to fall in extremely close to what Leupold says it should on the Varmint Reticles hold over bars.

Thanks for reminding me not to assume...