I think you are speaking from a very short political memory. Or you're young enough to not remember anything more than 30 or so years media, or politics wise when it comes to SCOTUS.
I mean, I know I don't remember such things, but the record is there if you care to investigate. The NRA only became truly political in the late 70s. There was barely a gun lobby at the time, or at least one that was happy enough with how things had been going for the previous 200 years.
The NRA lobbied against the liberal gun control movement that started in the 60s, begun as part of the new secular liberalism of the New Deal and the Great Society. I was a member in '75 or '76 when after the NRA formed its legislative unit to deal with the onslaught of gun control measures attempted in the wake of the sixties' assassinations - JFK, RFK, MLK, Medgar Evars - so I'm pretty conversant with the history of modern gun control attempts, but I'm unaware of any shift by SCOTUS to the right on the Second Amendment until arguably
McDonald v. Chicago, which established that the Fourteenth Amendment extended Second Amendment protections (for the individual) and limitations (to government's power) just as with any part of the Bill of Rights. Prior to the sixties, generally only practical gun control measures, which were generally supported by the NRA and which were often crafted in consultation with the NRA, had the political power to be enacted. The NRA organized a Legislative Division in the thirties though, to deal with the flood of gun-control legislation stemming from the Saint Valentine's Day massacre and the mob violence of the Prohibition era, and the NRA butted heads many times with FDR's government in the latter's plans to control gun ownership. So I'm not sure it's accurate to say the NRA only became political during the late seventies. It would be more accurate to say the NRA was apolitical until the threats to the Second Amendment in the thirties, was again apolitical until the sixties, and was political during those times where the Second Amendment was under effective assault.
The first serious attempt at disarming all law-abiding American citizens was the 1968 Gun Control Act. Even the Warren Court generally recognized the Second Amendment as an individual right. Indeed, there is no such thing as a collective right; your "right" to bear arms furnished by government when directed to do so by government, without private gun ownership rights, would be no different from any historical State power to draft a levy or militia and send it to do the State's bidding - hardly a freedom to be enshrined in the Bill of Rights.