When using the Leica BDC system, the reticle adjustment can be made faster and easier if the (MOA or cm) graduated ring in the ballistic tower is replaced with a meter graduated ring. With this, we do not need to set click values ​​from a table or smartphone application, but directly the measured distance. The system works perfectly with all distance meters. The standard ring is simply replaced with a ring containing distance values, and the required shooting distance can then be directly set. From 12 rings, we can choose the right ring for our caliber and ammunition. How does the BDC direct adjustment ring work? Each of the 12 rings corresponds to one (12 types) of different ballistic curves, which are the same as the preset ballistic curves of the CRF 1600-B laser and Geovid HD-B models. Choosing the right ring 1. The table for choosing the ring can be seen among the other images or can be viewed here. The same table can be found in the Geovid HD-B binoculars and CRF-B rangefinder user manuals. 2. Let's compare the ballistic curve of our ammunition for long distances (e.g. at 300 meters) with the values ​​in the table for 300 meters. 3. Select the ballistic curve data that best matches our ammunition. For quick reticle adjustment, install the appropriate direct adjustment ring instead of the standard ring. All we have to do is to loosen and remove the two hex screws of the upper knurled disc. Once this is done, lift out the knurled disc and replace the ring. Inserting the ring incorrectly is impossible. An example for identification: NORMA Oryx .300 Win. In the case of Mag., the ballistic data of the ammunition are as follows: 100m 0cm 200m -9cm 300m -34cm From the Leica tables, select the table with a zeroing distance of 100m, then find in the "300m" line which value is closest to -34cm. -34cm falls between "-32.4" and "-37.5", but is closer to "-32.4". We look at the EU value at the top of the column, in this case "EU3", so this ammunition corresponds to the "EU3" ballistic curve. If the data of the ammunition is not indicated on the box or in the catalog, or if it is not given in metric units, Leica's ballistic calculator can help, where you can enter the data and get the metric units. The program is available here. Below are some examples of classification. 243 Win. Norma Oryx 6.5g EU 6 257 Wby.Mag. Accubond 110 gr, 7.13 g EU 1 30-06 GECO Plus 11g EU 6 300 Win. Mag. Norma Oryx 11.7g EU 3 300 WSM. Norma Oryx 11.7g EU 5 338 Blaser Mag. Blaser Nos. Accubond 13g EU 3 8x68 S Norma Swift-A Frame 13g EU 4 9,3x62 Brenneke TOG 16g EU 6 375 H&H Norma African PH SN 22,7g EU 11