Frequently Asked Questions

1. What does CDS stand for?
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Custom Dial System
2. What does BDC stand for?
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Bullet Drop Compensation
3. Doesn’t my scope already come with a "CDS" dial since it's in the scope description?
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While your scope does come with an external dial, it's not calibrated to your specific load yet. Your scope comes with a 1/4 MOA or .1 MIL scale dial. To get your custom dial, please refer back to the order page.
4. Will my dial be free?
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Only scopes with "CDS" in the description on the box qualifies for one free BDC dial. There will be an insert card in the box explaining that you get one free dial.
5. Can my scope accept a BDC dial?
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If your scope has a removable dial attached with a set screw(s), or is a VX-6, then we can make a custom engraved BDC dial for it (does not apply to Competition series scopes). If your scope doesn’t have a removable dial, we may still be able to retrofit your scope to accept a BDC dial. Call 1-800-LEUPOLD with the scope in hand and we can discuss your options.
6. What is "ballistic coefficient" and where can I find it?
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The ballistic coefficient, or "BC", is a numeric figure that describes the bullets ability to overcome resistance cause by atmospheric conditions. Basically, how efficiently a bullet flies through the air. Most ammo manufactures don't include BC on the boxes. You'll most likely need to visit the manufacturer's website or contact them directly.
7. What is "zero distance"?
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Your zero distance is the yardage that you choose to sight in your rifle at. Most customers choose a 100yd zero but there are some that opt for a 200 or 300yd zero. While some customers who are building a dial for a rimfire rifle may want a 50yd zero.
8. Does my dial come with a zero-stop?
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While most dials do come with a zero-stop function. here are several types of dials which do not which includes M1 and target dials.
9. Does my dial go below my zero distance?
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No, the zero distance that you provide us with will be the lowest yardage mark on the dial.
10. What kind of distance will I get on my dial?
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The maximum distance on your dial will depend on the drop of your particular round and environmental factors. This is influenced by muzzle velocity, zero distance, and the type of adjustment on your scope. Most centerfire rifles will get 500-700 yards of bullet drop in one turn of a custom dial.
11. How do I measure sight height?
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To measure scope height, place the bottom of a ruler at the approximate center of the bolt. Measure from this point to the center of the scope tube. A typical hunting rifle will measure between 1.5 to 1.75 inches and an AR platform measurement will typically be 2.75 inches.
12. Should I chronograph my load?
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Yes, we recommend that you chronograph the load you're shooting to ensure the data on the dial is accurate. While the ballistic info on the ammo box will be close most of the time, there's no substitute for the exact ballistics. The dial will only be as accurate as the info that you provide.
13. How much buffer do I have for my environmental factors?
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For average elevation, you have about 2000ft of leeway on each side. For example, if you built a dial for 5000ft, that dial will be accurate down to 3000ft and up to 7000ft. The same goes for average temperature; you have 20 degrees on each side. So a dial built for 40 degrees is good down to 20 and up to 60.
14. Do you use G1 or G7 when calculating ballistics?
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When running a custom dial through Leupold's ballistic calculator, we use the G1 number. The difference between the G1 and G7 are so minimal at distances within 1800 yds, that you can’t dial the difference. For example – running the ballistics on a .308 190gr Nosler Accubond, you wouldn't see a difference on the custom dial until you hit 1700 yards. The max yardage we laser onto custom dials (model specific) is 1550 yds.
15. Can I get more than 1 revolution on my custom dial?
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Most CDS dials are designed to be 1 revolution dials. We can by request remove zero stops but we don't recommend it.
16. Why don't we factor in barrel length?
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True muzzle velocity has more of an effect on the accuracy of the dial rather than the barrel length. Longer barrel length usually have higher muzzle velocities but not always. Barrel length is not a reliable indicator of velocity. For the best accuracy, an average of a chronographed load is best. Your barrel length may differ from the barrel length the ammo manufacturer used to generate the ballistics printed on the ammo box.
17. Should I have a custom windage BDC dial made?
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We can make a custom windage BDC dial but windage dials do have limitations. We can only calculate and engrave the dial for 1 direction and 1 speed. Most likely it will not meet the conditions you are shooting in and may cause more confusion than benefit.
18. Can I use my dial at any magnification?
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Yes, the CDS dial system works the same way regardless of the magnification your scope is set to.
19. Can different types of dials be customized?
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Yes, scopes that have M1, M2, M3, M5, P5, M6C1, M5B1, M5B2, M5C2 and Target dials can be customized.
20. Can I get the CDS system on an older scope?
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Most likely the answer is yes. We can install the CDS system on scopes dating all the way back to the late 1980’s. But please call 1-800-LEUPOLD first before sending in product so we can verify the modification can be done.
21. Can I get more than one custom BDC dial?
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Yes, you may order as many as you would like. While you do get one free dial per CDS scope you purchase, additional dials may be ordered from $60.00 - $80.00 per dial. Please call 1-800-LEUPOLD to order any additional dials.