Bullet Drop Compensation (BDC) scopes use a specific pattern of reticle that shows you how far bullets will drop over a said distance. Whenever we use a scope, the reticle always has multiple aiming points stacked under the actual main crosshair. We can even say that a BDC reticle is kind of like a reticle inside a reticle.
In these BDC scopes, the manufacturers put either specific reticles or they use specialized turrets for calculating the distance that a bullet drops over a specific distance. Whenever a bullet exits a rifle barrel, gravity starts working on it as it moves towards the intended target.
This effect can cause the bullet to move down so, the aim needs to be a bit high when you are shooting from a range. The shooter needs to compensate for this “bullet drop” by aiming higher basically. This is a technique that professional shooters call “holdover.”
For calculating the holdover, we need to have data on things such as the size and speed of bullet, distance to the target, magnification for the shot, bullet’s coefficient and much more! A BDC scope basically does the work for you and the reticle and the turrets in it make your job easier as a shooter.
How do the BDC Scopes function?
Most BDC scope have two main parts that do the main function
Traditionally, scopes use duplex reticle. BDC Reticles are way different than that. They have marks that are easy to see. These marks start just below where the crosshair is and extends all the way down the verticle post of crosshair.
The BDC reticle marks comes in different shapes like Micro-dots, Open Circles, Hash Marks, Diamond Shaped Marks.
Some scope brands also have a secondary mark between each of the primary marks to get even better BDC for the shot. Every BDC based sight marks can correspond to a certain distance. So, the first BDC reticle can say that the target is 100 yards from the crosshair, the second reticle might be 200 yards and so on.
Depending on the size of bullet, type of scope and the gun’s weight and model, A BDC scope can offer you much flexible shooting at a distance that exceeds even 800 yards sometimes. This is cool, right?
The BDC reticle is the more common and famous option for BDC, the turrets are also used in some specific cases. A lot of people actually prefer turrets.
Just like the reticle, most BDC turrets have specific caliber and they also give you the BDC option. The selection between the two is up to the shooter. A BDC turret has different markings to denote different shooting distances.
There is a small knob that can be turned to pre-set distances when using the turrets. Do this once the turret has been configured correctly. The turrets are able to calculate the basic math for BDC. The distance is actually already built into the turret.
A shooter using the 22LR scope with a BDC turret would need to turn the turret to the designated 100 yard marking and then shoot the target while they are holding the reticle. You don’t need any holdover for it as ut is pre-configured into the turret.
Benefits and Limitation of BDC scopes
One of the main benefits of BDC scopes is that the aiming points correspond to the bullet impact at a pre-determined distances.
These distances are often set at the multiple of 100 yards. Some scope do offer 50 yards incremental distance aiming points though. If you practice it enough, you can really improve your shooting by quite a margin with a BDC scope.
Another reason the BDC scopes are so well received is because the shooter does not have to adjust the scope’s elevation while they are taking a shot. Instead of this, you can simply find the right line to take the shot.
Everything has disadvantages, cons and limitations. The BDC’s first limitation is that they are for generalized points. So, at 100 yards, 200 yards or 300 yards they do the job. But about say, 167 yards? What if your target is this far away? The BDC reticle will not really help you out in this situation. Turrets might help though, if they can be set to this distance.
We also need to shoot specific rounds with a BDC reticle at a specific distance in a consistent manner. Any detour from this can cause a missed shot.
But then again, it all boils down to practice. If you constantly use BDC reticles and are good at using it, everything just becomes easier for you.