Gracias sir.
I switched the rear sight on my MR556 to an HK 93 drum so as to get the V notch on the 1 setting because the full hood on the MR sight cluttered my Aimpoint sight picture too much, and then I realized that if I set my sight distance apart correctly, I could actually take advantage of the BDC ability on the rest of the drum settings.
Your help is greatly appreciated!