"I doubt the founders had any idea of the type of weapons that would be available in this day and age. I wonder how we are interpreting "a well regulated militia?" What does "well regulated" mean? What does "Militia" mean?
The full Amend is: "A well regulated milita, being necessary for the security of a free state, the right of the people to keep and bear arms, shall not be infringed."
The subject of the sentence is, "the right" The verb is, "shall not be infringed." The adjective phrases describing the right are, "of the people", and "to keep and bear arms". They describe hte right. The leading clause has the effect of a whereas, it does not describe the right in any way. It is not the govm't's right, it is the people's right, not the militia's right, or the sheriff's right.
It's clear from what all the founder's wrote, and their own actions, that they intended to protect the right of the people to keep and bear arms, to enable the people to effectively challenge tyranical acts of the govm't. They intended the people to be able to kill soldiers of the king's army, or any other army, or nband of criminals acting to deny Freedom. Note the people as individuals are the militia, not some State, or fed org. Note the intent is to protect Freedom, a Free State, not simple the state, but a "Free state. Authoritarian rule and socialism didn't fly with the founders, Freedom did. They respected and honored their fellows that had supported Freedom, and those tht would in the future by penning the Amend. Note the promise of the Bill of Rights, is why folks supported the signing of the US Constitution in the first place.
The arms protected were those necessary and sufficient to oppose the tyranny of the govm't. They assumed, as is reasonable and prudent, that no one in their right mind would ever deny a man's ability to mount an effective self defense against murderers, road agents, rapists and all those various unenumerated scumbags that exist.
Your fellow Americans are not child murderers, or bad guys. The do not assault schools, rob folks, plot to overthrow the govm't, and kill kill folks for no reason. They are not closet bad guys. They are not to have their rights denied by prior restraint, as if they are all closet scumbags and equal to the least common denominator of heinous murderers.