Not sure if this applies to everyone here but there is one thing most people do not realize about a BDC reticle.
Without going into a lot of detail there are two types of scopes, First focal plane and Second focal plane.
With first focal plane, as you adjust the magnification the reticle will increase or decrease in size as you zoom in or out. It scales proportionaltly with the magnification.
With a second focal plane scope the reticle will appear the same size regardless of the magnification.
Vortex has a good video describing the two designs:
Most scopes sold are of the second focal plane design.
The thing that most do not realize is that the BDC, mil dots, etc are only accurate at ONE magnification, usually the strongest.
They are also calibrated using a specific bullet weight at a specific velocity at a certain elevation at a specific temp, etc. Change any of those factors and you change the ballistics and will have to manually adjust. BDC scopes can be very effective but you have to know the ballistics of the ammo you are shooting and how they correlate to the marks in the scope. I believe NIkon used to, any may still, provide a calculator to tell you how your specific ammo will correlate to their BDC.
As a side, speed adjustable crossbow scopes are second focal plane BCD scopes. You tune them for the speed of the bow by zooming in or out until you find the magnification that matches the drop from 20 to 30 to 40 yards, etc. Once dialed in you cannot change the magnification or you screw up the settings at different yardages.
If you already know this, OK, but perhaps it will help sopmeone who does not.