The framers meant muskets! It was what was needed to defend against other muskets. If our gov’t has much stronger weaponry than citizens, we are subject to be subjects again!
I think when one looks at historical context as to who owned the cannons used in the revolutionary war as well as harp guns, duck foot pistols, grenades, bombs, ships of war, etc, that there was never any original interpretation of it simply meaning muskets. Nor do arms limit to firearms, but includes all weapons and tools of defense including swords, knives, and heck, even pitchforks and brass knuckles.
All of these interpretations have one singular goal, to eliminate the natural right of self defense. Defense against any aggressor be it neighbor or government.