The New York Times mentions this:

[McCain] is reveling in big-time Republican endorsements that may soon include, he hopes, support from the National Rifle Association.

I would be very, very surprised if the NRA endorsed in the Republican presidential primary, and I would be surprised if they could give a full-throated endorsement of McCain over Romney. It’s not that Romney doesn’t have his flawsl it’s just that the NRA had extremely strong opinions about McCain’s campaign finance reform which led to descriptions like this in NRA publications:

McCain was led down a primrose path by a Senate Democratic leadership that is doing all it can to keep him beholden. In reality, it is pushing to derail President George W. Bush’s chance for a second term. And more importantly, it wants a Senate majority of radical Democrats. And that would prove an unprecedented threat to the Second Amendment. John McCain is its Judas goat–leading the sheep to slaughter.
McCain’s relationship with the Democratic leadership paid off when he demanded to bring his campaign finance bill directly to the floor. By doing so, McCain short-circuited the entire normal, deliberative hearing process. Not one word of testimony in the first Senate session of the 107th Congress was heard on campaign finance reform. Not one ordinary American appeared in support or opposition to this legislation. That blackout of public comment was McCain’s ace in the hole.

That was in 2001. Also that year, Wayne LaPierre asked, “Is it possible that John McCain thinks you have too much freedom?”

McCain’s relationship with Second Amendment advocates has warmed – he got at the very least a polite reception at the NRA’s candidate forum last fall. (Huckabee’s speech was a grand slam, however.) And I wouldn’t be surprised if the NRA decided to endorse in the general (Hillary and Obama are awful in their eyes). But I don’t see them shifting away from primary neutrality.