Bdl, if there is a problem with cases in the magazine you just hit the button and they all fall out. Quick and easy, I'm really not sure why this is even a discussion. Either you see a need for Bdl or the adl. There isn't some super secret to either. Personally on the 300 I would run a bdl. I do not see the need for a dbm or an internal magazine system with a rifle of this caliber.