Don't get me wrong. I support H.R. 1036, even though it means violating the basic principles of the Constitution. Unfortunately, our governments and society are so out-of-control, that we have to break some rules to get things back on track. I'm not happy about this, because it leads us down the slippery slope that got us into this mess to begin with.
That said, I still support Ron Paul and his position on this matter. The true mark of a responsible leader is one who does what is right, even if it is unpopular.
It is childish for the NRA to threaten to pull their support from Rep. Paul. Worse than that, it gives power and propaganda to his political opponents--and the NRA's. Instead, they should laud Rep. Paul and hold him up as the ideal to which all Congressmen should aspire (especially, the so-called "conservative" ones).
I would respectfully suggest to both you and Mr. Paul that Congress has exclusive authority over interstate commerce. Given that the stated intention of these lawsuits is to interfere with the lawful interstate commerce of firearms, I don't think it's a stretch to state that barring such lawsuits is a "necessary and proper" means of Congress exerting its authority.
Alternatively, with some slight changes to the bill, it could be made to pass muster under the "Full faith and credit" clause which lets Congress determine the effects of judicial actions in one state on another: using that power, Congress could declare all judicial actions against firearm manufacturers in other states to be null and void.