I too live in Ma and have been to Ron Glidden's class. Glidden is the guy who writes most off these laws. A pre-ban mag is a pre ban mag. unless its been altered from its original configuration. IF your analogy was true a person who purchased a Mass complaint AR would be in violation if they used a pre-ban mag in it. The same would be true in regards to using pre ban mag in a new handgun, for example a new sig P-226 or Beretta 9mm with an older Pre-ban mag.