@shootist~
If you have a collimator you can check you reticle spacings at any power. I did that with my son's scope. Set some 600ml bottles at 400 yards, told him the dopes and let him shoot. Took him a while to get the first bottle and told me my dopes were wrong. Problem was he was using 5 power not 9. After he set the scope on 9 power and used the dopes I told him he hit all the next bottles first shot.
With a bdc reticle, even one that has a balistic app it pays to shoot it at longer range to confirm the setting.
Even good quality scopes can be out. Are the clicks quarter inch at 100 yards or 1 centimetre at 100 meters or even moa clicks. You need to know.at shorter ranges it's no big deal but as range increases it can make a big difference.
Bob