It's the common definition at the time it was written that mattered and in the 18th century well regulated meant in proper working order not government controlled
Second Amendment
A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.
What is the Militia?
The Founders believed that all men between the ages of 18 and 45 who were physically capable were members of the Militia. It was up to these men to be the first line of defense against any enemy attack.
In United States v. Miller, 307 U. S. 174, 179 (1939), we explained that "the Militia comprised all males physically capable of acting in concert for the common defense." —Supreme Court of the United States (District of Columbia v. Heller) Page 22
The Militia is not created by Congress, nor is Congress empowered to create a militia.
Unlike armies and navies, which Congress is given the power to create ("to raise . . . Armies"; "to provide . . . a Navy," Art. I, §8, cls. 12–13), the Militia is assumed by Article I already to be in existence. Congress is given the power to "provide for calling forth the militia," §8, cl. 15; and the power not to create, but to "organiz[e]" it—and not to organize "a" militia, which is what one would expect if the Militia were to be a federal creation, but to organize "the" Militia, connoting a body already in existence, ibid., cl. 16. This is fully consistent with the ordinary definition of the Militia as all able-bodied men. —Supreme Court of the United States (District of Columbia v. Heller) Page 23
What does well regulated mean?
Finally, the adjective "well-regulated" implies nothing more than the imposition of proper discipline and training. —Supreme Court of the United States (District of Columbia v. Heller) Page 23