Gun rights has always been an orphan issue politically because it's a populist, libertarian issue; it's fundamentally about the government having less power and control, while government is inherently all about having power and control. For decades gun owners have had to choose between Democrats who are actively crusading against guns, and Republicans who most often pay lip service to gun rights while doing precious little to uphold them.
I think the best we can do is track actual voting records on proposed gun laws, and remind our representatives that their support for gun rights or lack thereof will be kept in mind the next primary, if a challenger promises to do a better job. At this point the primaries are where votes really count.