The NRA did support red flag laws as of about a year or so ago, if even that long ago - I don't know the date. There was a video of Chris Cox, speaking for the NRA, urging support for getting them passed. I did see that video on the NRA site at that time.
I could not find a link to that video in a very quick web search today, but I did find a brief clip of the Chris Cox video embedded in this other video on You Tube. The very brief Chris Cox clip can be seen starting at about the 6:30 mark in the video at this link:
https://www.youtube.com/watch?v=F6bzaXdKwaY
I can't specify the particulars of the NRA support for these laws at that time, nor if or how they support them now. All I know is that they did support red flag laws at one time.