Leupold CDS concerns

benclark74 · October 11, 2016, 11:49 AM

Hi everyone! This is my first post to this forum, I'm looking forward to many more and helping out whomever I can.

I'm shooting a Tikka hunter .308 win with a Leupold VX-3L.

Well a couple of weeks ago I received my CDS from Leopold and upon its arrival I immediately noticed that there had been a miss communication over the phone while I was giving them the ballistic facts for my ammunition. The dial was built for 150gr Nosler trophy grade accubonds, which have a muzzle velocity of 2875fps but the CDS I received reads 2750fps. I took it to the range yesterday and at 100yds its a tack driver, but the purpose of the CDS is for taking long range shots. My concern is if the 125fps difference will cause the dial to be less effective out to 300 or 400 yards.

Thanks for any input.

Kimber84 · October 11, 2016, 03:08 PM

Didn't you give them drop data? Without that you'll just be relying on a ballistic calculator to come up with your drop and without chronographed speeds it's anyone's guess where the bullet will be at any given range.

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jmr40 · October 11, 2016, 03:16 PM

Shoot it and see what happens. My guess is that it'll be close enough to make hits on big game. At worst you may find that you'll have to adjust the CDS by an extra 25 or 50 yards. In other words if the target is exactly 300 yards away you may find setting the CDS on 325 yards gives you a better zero. At 400 yards you may have to set it on 450. When hunting you rarely have game at exactly 100,200, 300 or 500 yards like at the range. You almost always get 137, 213, 376, etc when you hit it with the range finder so I don't think this is something that can't be overcome. Lots of people use a generic dial system and find it close enough. If you're not happy with the results contact Leupold for another custom dial.

Once you get to 300-400 yards group size is large enough to make precise use of a CDS or dot sight impractical anyway. If you and your rifle are still able to keep 1" groups at 400 yards, then it might matter.

jmr40 · October 11, 2016, 03:19 PM

Quote:

Didn't you give them drop data? Without that you'll just be relying on a ballistic calculator to come up with your drop and without chronographed speeds it's anyone's guess where the bullet will be at any given range.

There is no drop data to give. They want the caliber, bullet weight, Bullet BC, and measured MV. The data is used with a ballistic calculator to build a custom dial. Someone got the MV wrong. Either the OP gave them the wrong MV or someone at Leupold got it wrong.

HiBC · October 11, 2016, 03:25 PM

I do not have a CDS. I think via the custom shop you can give specific info for a custom knob.Other than that,there are generic knobs "in the zone"

Call the custom shop,look at the web page.

There are always variables from the knob.Altitude,your bullet BC,temp,etc.

I have a custom target knob made by Kenton Industries for a Leupold Long Range scope for a particular load,chrono'd velocity etc. Dial-a Range.It works pretty good.But allowances have to be made.

If Leupold says that is the best knob for you,you can go on the Hornady page and use their ballistic software.You want to "overlay" the curve of the ballistics on your knob with the curve your bullet will fly,at your hunting altitude and temp.You can try different sight in ranges to minimize error.
Generally,a longer range sight in,like 300 yds or more,is the best compromise.As the ranges get shorter,the error will be smaller.

I'm saying calibrating it at 100 yds may get you a 6 in error at 300 yds.Calibrating it at 300 yds would get you a 2 in error at 100 yds.

A 2 in error is a smaller miss than a 6 in error.

Kimber84 · October 11, 2016, 04:02 PM

Quote:

Originally Posted by jmr40

There is no drop data to give. They want the caliber, bullet weight, Bullet BC, and measured MV. The data is used with a ballistic calculator to build a custom dial. Someone got the MV wrong. Either the OP gave them the wrong MV or someone at Leupold got it wrong.

I gotcha.

I guess Kenton industries does it based off of actual recorded drop data. That's been the only place I've had custom turrets made.

The concern I have with what the OP said is it sounds as though the velocity may have come from the published numbers not actual chrono'd values. Maybe I'm interpreting it wrong???

I have a CDS, but again I just established my drop to 500 yards on my .204 then derived incremental adjustments based on range, from that I made a dope chart.

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benclark74 · October 11, 2016, 04:21 PM

Thanks for all the info guys. I guess I'll try some long range shots and see where I'm hitting. I will very rarely be shooting further than 300 yards so as long as its good up to that I'll be satisfied.

eastbank · October 11, 2016, 07:01 PM

shoot it dead on at 200 yards and then move the dial to-o and then shoot it at 300 yards, counting the clicks that get you on at 300 yards. eastbank.

benclark74 · October 15, 2016, 09:47 PM

I went out to my wife's grandfathers farm yesterday to see what she could do, so using my rangefinder I set out an empty 4 quart jug of transmission fluid filled with water at 310 yards. Turned the dial up to 3 and put the crosshairs dead center on the jug. I wish someone had taken a picture of my smile when I squeezed that trigger and saw the jug explode...very satisfying. So much so that I shot two more jugs

I've always been a fan of Leopold products but after this I'm sure this will be the brand I stick to.

October 11, 2016, 11:49 AM	#1
benclark74 Junior Member Join Date: October 11, 2016 Posts: 3	Leupold CDS concerns Hi everyone! This is my first post to this forum, I'm looking forward to many more and helping out whomever I can. I'm shooting a Tikka hunter .308 win with a Leupold VX-3L. Well a couple of weeks ago I received my CDS from Leopold and upon its arrival I immediately noticed that there had been a miss communication over the phone while I was giving them the ballistic facts for my ammunition. The dial was built for 150gr Nosler trophy grade accubonds, which have a muzzle velocity of 2875fps but the CDS I received reads 2750fps. I took it to the range yesterday and at 100yds its a tack driver, but the purpose of the CDS is for taking long range shots. My concern is if the 125fps difference will cause the dial to be less effective out to 300 or 400 yards. Thanks for any input.

October 15, 2016, 09:47 PM	#9
benclark74 Junior Member Join Date: October 11, 2016 Posts: 3	Well I'm happy with the results.... I went out to my wife's grandfathers farm yesterday to see what she could do, so using my rangefinder I set out an empty 4 quart jug of transmission fluid filled with water at 310 yards. Turned the dial up to 3 and put the crosshairs dead center on the jug. I wish someone had taken a picture of my smile when I squeezed that trigger and saw the jug explode...very satisfying. So much so that I shot two more jugs I've always been a fan of Leopold products but after this I'm sure this will be the brand I stick to.

October 11, 2016, 03:08 PM	#2
Kimber84 Senior Member Join Date: April 8, 2013 Location: US Posts: 455	Didn't you give them drop data? Without that you'll just be relying on a ballistic calculator to come up with your drop and without chronographed speeds it's anyone's guess where the bullet will be at any given range. Sent from my iPhone using Tapatalk

October 11, 2016, 03:16 PM	#3
jmr40 Senior Member Join Date: June 15, 2008 Location: Georgia Posts: 10,805	Shoot it and see what happens. My guess is that it'll be close enough to make hits on big game. At worst you may find that you'll have to adjust the CDS by an extra 25 or 50 yards. In other words if the target is exactly 300 yards away you may find setting the CDS on 325 yards gives you a better zero. At 400 yards you may have to set it on 450. When hunting you rarely have game at exactly 100,200, 300 or 500 yards like at the range. You almost always get 137, 213, 376, etc when you hit it with the range finder so I don't think this is something that can't be overcome. Lots of people use a generic dial system and find it close enough. If you're not happy with the results contact Leupold for another custom dial. Once you get to 300-400 yards group size is large enough to make precise use of a CDS or dot sight impractical anyway. If you and your rifle are still able to keep 1" groups at 400 yards, then it might matter.

October 11, 2016, 03:25 PM	#5
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,283	I do not have a CDS. I think via the custom shop you can give specific info for a custom knob.Other than that,there are generic knobs "in the zone" Call the custom shop,look at the web page. There are always variables from the knob.Altitude,your bullet BC,temp,etc. I have a custom target knob made by Kenton Industries for a Leupold Long Range scope for a particular load,chrono'd velocity etc. Dial-a Range.It works pretty good.But allowances have to be made. If Leupold says that is the best knob for you,you can go on the Hornady page and use their ballistic software.You want to "overlay" the curve of the ballistics on your knob with the curve your bullet will fly,at your hunting altitude and temp.You can try different sight in ranges to minimize error. Generally,a longer range sight in,like 300 yds or more,is the best compromise.As the ranges get shorter,the error will be smaller. I'm saying calibrating it at 100 yds may get you a 6 in error at 300 yds.Calibrating it at 300 yds would get you a 2 in error at 100 yds. A 2 in error is a smaller miss than a 6 in error.

October 11, 2016, 04:21 PM	#7
benclark74 Junior Member Join Date: October 11, 2016 Posts: 3	Thanks for all the info guys. I guess I'll try some long range shots and see where I'm hitting. I will very rarely be shooting further than 300 yards so as long as its good up to that I'll be satisfied.

October 11, 2016, 07:01 PM	#8
eastbank Senior Member Join Date: February 7, 2008 Location: pa. Posts: 2,450	shoot it dead on at 200 yards and then move the dial to-o and then shoot it at 300 yards, counting the clicks that get you on at 300 yards. eastbank.