Mixing & (mis)matching definitions are why we never seem to get anywhere in debates with gun-controllers like BoR.
We can infer that BoR thinks of a "heavy weapon" as an automatic weapon that puts out a high-volume of fire. The military definition of a "heavy weapon" is basically any weapon that isn't easily man-portable by a single soldier. Therefore, a Squad Automatic Weapon (.556) is a light-weapon as it is handled by a single-soldier while a M2 (Ma Deuce) machine gun requires a crew (or is vehicle mounted).
Seems we keep running into these problems because few if any liberals have military experience. When you 'school them' they just change the subject or start arguing another fine-point about which they know nothing.
Concur with both, and seconded...