I think any left-of-political-center gun rights supporters are perfectly welcome in my NRA and in The NRA. The story's overblown. The truth is that, generally, pro-gun, pro-hunting, etc. is much more often a position held by people that are more conservative. Traditional, constitutional (more strictly so) values are the hallmark of conservatism which doesn't necessarily mean "Republican" as much as it means a preference toward measured change. The polarization of our times has coopted some of this, but the two parties have also embraced the competing sides of this issue. The only Democrats (besides the odd Harry Reid or Tom Daschle type) that embrace gun rights tend to be people like Heath Shuler or other "Blue Dogs" (which used to be moderative-to-conservative Democrats)...and they are viewed negatively within their party's central organization. Gerrymandering (by both parties) has exacerbated this polarization by allowing more extreme politicians to remain electable by both parties.
Don't get me wrong, my views are pretty conservative, but our issue (2A) has become my main issue because it speaks to many other values I hold dear. Generally, somebody that supports gun control/elimination is also a fan of bigger government, more government intervention in our lives, less self-determination, etc. I would love to see this one get de-coupled from party issues.
As for the NRA supporting ALEC, since there are only 4MM NRA members, and probably 20 times that in people that are pretty conservative but don't join up, it makes sense for the NRA to chase as much low hanging fruit as possible. Thankfully, we have also seen the beginnings of some nice outreach to the African American community (Otis MacDonald was great here) and some other growing constituencies should be on the NRA's radar. I imagine retirees, handicapped people, gay people,....I can see lots and lots of potential value in CC for people that historically wouldn't align with the average hunter.
We need to do more outreach, but I think the NRA should be "A Big Tent" and I have been supportive of that.