I find it somehow hard to believe that it was universally believed to be personal right only by recent activists, as many state constitutions explicitly treat it as personal right[1].

If people writing those constitutions didn't believe such personal right exists and is important, why would they write so?

There are known examples of prominent lawyers supporting such understanding in 19th century. [2]

It is also hard to believe if you read historical reviews about various gun laws in 19th century [3], where while the public carry of guns was often restricted, nobody doubted the right of people to actually own them, and nobody referred to "collective right" as the reason.

I can appreciate the difference in approaches, but the claim that "individual rights" approach did not exist until recently - and not as a crazy idea in minds of a small bunch of "activists", but as widely recognized and adopted concept - seems to contradict all evidence. NRA was founded in 1871, not exactly "a few decades ago", but "individual rights" interpretation existed and was widely accepted way before that.

[1] http://www.davekopel.com/2A/LawRev/19thcentury.htm#N_191_ [2] http://www.davekopel.com/2A/LawRev/19thcentury.htm#St. George Tucker [2] http://fabiusmaximus.com/2013/01/24/guns-wild-west-48208/