I am an NRA member, but do not rely on the NRA to tell me how to vote or what bill to support. It could be that other NRA members feel similarly.
I like the current NICS system just fine, and they don't need to change it. I also like the fact that I can buy or sell a firearm within my state without a NICS check. I have bought a few firearms that way, and I would like to continue to do so, since going to a place with an FFL would be an incredible pain in the *** for most sellers and buyers.
I have bought rusty guns for less than $50 before - completely on a whim. If I had to say "hey I'll give you fifty bucks for that, but we'll need to take it to Bubba's gun world to do a background check first", then that spur of the moment whim would wane, rather quickly.
That's why I oppose it, not because the NRA tells me to, or because I simply am a member of the NRA. I think the NRA is full up on their "nutball" quota as it is. I don't need to join in the mob mentality, and I would urge everyone to learn about issues and figure out where they stand by themselves.