When it was written, “well regulated” meant adequately armed. The “militia” was every able-bodied white male between 16 and 45.
Legislate all you want. You will disarm us at your own peril.
...also meant disciplined at the time of nearly early historical greek/roman warfare.
Troops lined up against each other, fired until the the other broke, and then ran down the remnants with cavalry or light infantry.
Here is an example of well regulated command inflection from a militia leader:
Double time march!
Quick time march!
Unit Halt!
Right Face!
Fix Bayonets!
Front rank kneel!
On my command: Volley fire by ranks 1,2,3!
Fire!
Reload!
At the ready!
Right Face!
Double time march!
If you didn't know what the above commands were, your unit would look like a soup sandwich and melt on the battlefield. You had to be well trained/regulated to perform battlefield actions in the 18th century.....and the 8th century for that matter.