No it wasn’t and we know the original meaning of the phrase 'Well Regulated".

“A well regulated clock keeps proper time”.

It simply means to work as designed and/or efficiently.

You can’t quickly raise a civilian militia that is either effective or efficient in times of emergency unless they are already armed and well versed in using their arms.

The following are taken from the Oxford English Dictionary , and bracket in time the writing of the 2nd amendment:

1709: “If a liberal Education has formed in us well-regulated Appetites and worthy Inclinations.”

1714: “The practice of all well-regulated courts of justice in the world.”

1812: “The equation of time … is the adjustment of the difference of time as shown by a well-regulated clock and a true sun dial.”

1848: “A remissness for which I am sure every well-regulated person will blame the Mayor.”

1862: “It appeared to her well-regulated mind, like a clandestine proceeding.”

1894: “The newspaper, a never wanting adjunct to every well-regulated American embryo city.”

https://constitution.org/cons/wellregu.htm