First of all, congrats on landing a great trade! The Browning A-bolt is a fantastic rifle.

Even if the BDC doesn't correspond exactly, it'll probably still be useful. You might end up having to use the bottom or top of the circle instead of the center of the circle to aim at longer distances. You may even need to just frame the kill zone between circles. Either way, it'll be better than trying to compensate distance without a BDC.