December 29, 2010
Leupold’s CDS Explained: Part I
By David E. Petzal
by David E. Petzal
As I revealed in my post of December 22, Leupold has a new range-compensating system called CDS which offers some major advantages to those of you who yearn to hit things Way Out There. Here’s how it works:
1. Buy a Leupold VX-3 scope equipped for the CDS system. (There are five models from which you can choose.) The scope comes with a “sighter” elevation dial that you use for getting the scope on target.
2. Figure out which loads you want to shoot at long range and then call the Leupold Custom Shop (1-800-LEUPOLD) so they can make you a custom dial. Provide them with the diameter, ballistic coefficient, bullet type (spitzer, round nose, etc.), muzzle velocity (it helps if you have a chronograph so you can give them what you’re actually getting), the average elevation and temperature at which you shoot, and whether you intend to zero the gun at 100 or 200 yards. The price is $50 per dial.
3. Leupold will then calculate how many clicks you need so that you can hit dead on at ranges from 100 to 600 yards, and will laser-engrave the yardages and index lines on an elevation dial. They will also engrave the info you give them on top of the dial so you can’t get it confused with another one.
4. Once you have your custom dial(s) you sight your rifle in to hit dead-on at 100 or 200 yards. Then, loosen the three tiny set screws that hold your sighter dial and replace it with the custom dial of your choice. Line up the “100” marking on the new dial with the index line on the turret, tighten the three tiny set screws, and you’re done.
5. To use the CDS system in the field, lase whatever you want to put a bullet in and set the CDS dial to that distance. Then figure out what the wind is doing and pull the trigger. If you’re concerned that you’ll wear out the elevation machinery, be advised that Leupold has given the system as much as 2,000 full revolutions, continuously, and had no failures.
In Part II: my own excellent adventure with the CDS.