To properly calibrate the BDC you need to zero your rifle at 100 meters (yards will rougly suffice, but if you can get true 100 meters you will be better off). You can reduce some of your headache by expediantly zeroing at 36 yards using the third line down from center. With the carrying handle mount at 36 yards your group should be about 1 inch below POA.
You can also expediantly zero at 50 yards using the 200 meter (second line down) aim point. At 50 you should be about 1/2 inch POI below POA.
You don't really need to pull your hair out at close range, just get it reasonably close.
Then drop back to 100 yards/meters and establish your zero with the top crosshair. I really recommend that you use 10 shot strings to establish your zero at 100.
Don't forget: 3 clicks per inch at 100 (9 per inch at 36) and check the tightness of the screw after each string of fire.