Orin, I always recommend buying as many magazines for the firearms you own as you are personally comfortable with. I buy magazines as if they will disappear, both standard, extended/drums. There really no telling what would be confiscated in the future. Cheers and stay safe!

Even if they were to become illegal, there would be no way of tracking them as they are currently unregulated, they would grandfather in any of them that are already out there, and ban them moving forward, so I say stock up just in case.