I'm simply saying that "arms" is more a military term. "Guns" is more a civilian term. Do you agree?
I would say that "arms" is a better term, and it certainly leaves no question as to what is being discussed. "Guns", on the other hand, has a slang-like feel to it. Radar gun. Squirt gun. Nail gun. This is my rifle and *this* is my gun. It makes sense that the military would retain the proper terminology.
Nowadays, "arms" sounds more "military", but when the Bill of Rights was written, that was not the case. The American vocabulary has suffered much in the past, oh, 150 years.