I regularly read American Rifleman, the NRA’s official magazine. If you cut out the first 10 or so pages, it is an excellent magazine, easily the best magazine about firearms ever published, with great historical and technical writing, useful practical information sections, and wonderful reader service. If you’ve found a gun, inherited a gun, or even just randomly bought a gun, and you can’t figure out where its from or what it is, you can send them a picture, and they will often give you a very detailed run-down of who made it, when, and occasionally, what factory produced it.
This is, quixotically, the secret tell about the relationship between the NRA and the Industry that one can find in the magazine itself, as this research would often require exceptional relations with manufacturers throughout the industry to get access to the sheer volume of historically archived information that they often use to do those run-downs. The rest of the magazine is studiously, self-consciously scrubbed of industry ties, but usually the writers themselves, when reviewing guns, try to be fairly objective, or at least, appear to be. The writers, the actual content producers, are, in the magazine, generally apolitical and are knowledgeable enthusiasts and experts. Other than the ads (Many of which, particularly those for women, can be ridiculous.), there is little that jumps out and says “The Industry pays for this.”
Those first couple pages though, are where the political report goes, along with the legislative report, the “Armed Citizen” section which tells only positive, 1 paragraph blurbs of people lawfully shooting others in self-defense (Occasionally described in coded language that tells you what kind of people they are).
If you think what the NRA is saying now is outrageous and hyperbolic, well, the magazine does that basically every month. Wayne La Pierre in print is basically Wayne La Pierre on-stage. During the Obama years, it was a continuous litany of “They’re after your guns! Only the NRA can stop them! GIVE US MONEY!” now, they’ve gone back to their default stance: “LIBERALS WANT TO TAKE YOUR GUNS. STOP THE SPREAD OF ANTI-AMERICAN LIBERALS TRYING TO SABOTAGE YOUR STATE LEGISLATURES! ONLY THE NRA CAN STOP THEM IN THE COURTS! GIVE US MONEY!” Frequent targets are Michael Bloomberg, Coastal Elites, Liberals, and Elizabeth Warren.
But behind all of this rhetoric and frothing at the mouth prose that is, in the classical sense, propaganda, is a cleverly designed and highly effective legislative and issue monitoring system, which you can access through their website, in which they meticulously track each and every salient gun-related or gun-proximate issue in all 50 states. And I mean every issue. No matter how minor. If a city council is trying to ban lead ammunition because someone has a gun range next to the water supply, the NRA will know about it within a few days, and lobbyist and legal assistance can be readily requested.
But to your original question: The stance, agenda, and end point of the NRA can be summarized as a slippery slope defense. Their chief concern is that any attempt to create a legal basis for banning or prohibiting guns will be treated as a legal stepping stone for further restrictions, prohibitions, or seizures, a form of constitutional absolutism, which often gels with “Strict Constructionist” legal framework embraced by many conservatives. While they are intensely hyperbolic, they do genuinely believe in the basic kernel of their hype.
Specifically, many do legitimately believe - as many conservatives now do - that the Democrats, and liberals in general, are a stealth campaign for “European Socialism”. They then generally proceed to conflate that with National Socialism AND Communism, simultaneously, which they use as the keystone for the prohibition and seizure argument - “Because Nazis seized guns and disarmed the populace, no one could resist them, particularly not the Jews. The communists never let people have guns, so no one could oppose them either. Liberals want to take your guns, ergo they must have a sinister agenda, just like the Nazis and the Commies, and they also believe all those same things that the Nazis and Commies believe, which are not the things that Real Americans believe. As Real Americans, it is your duty to oppose them.” The subtext there is that guns would be integral to any farcical attempt to overthrow the government. The NRA is careful about how they phrase that issue - generally deferring to an appeal about “Resisting Tyranny.”
At the deeper levels of 2nd Amendment culture, which again has a broad nexus with conservatism, but is not always exclusively conservative, this argumentation can be delivered breathlessly, and without much examination or critical reflection, which I have heard first-hand. From a political science or rational thought perspective, this argumentation is fraught with logical failures, irrational appeals to emotional touchstones, threats, and a middle school level understanding of European history, which has itself then been further distorted. It is a political science nightmare that presents a convenient and erroneous pastiche of ideologies and their relationships to one another, which I’m convinced senior NRA leadership is aware is complete bunk.
To summarize, their final true goal is that there are no restrictions of any kind on firearms (My right to own and carry a Sword is not their purview, see the (relatively) more rational Knife Rights people), and that all gun-owners be networked into an activism network that promotes gun-ownership and issue mobilization. The NRA has positioned itself as the logical nexus of those two lines of thought. This is the foundation of their business model, each aim reinforcing the other and thus, justifying its existence. It is an eternal war for an absolutist interpretation of the 2nd Amendment. In this war, the prevalence of constitutional absolutism within Conservatism, as well as the demographic overlaps with gun-owners, is the basis of their political alliance. Because the NRA grounds itself in the absolutist and unequivocal interpretation of the 2nd Amendment, opposition to the NRA means that one believes the 2nd amendment, and thus the constitution, is not absolute. This would mean it could be changed or reinterpreted or ignored. This in turn would indict one’s conservative principals, and thus make one a liberal. Its not simply about the NRA giving conservatives money. Its a deeper alignment between the ideologies and issues that has been very carefully constructed over the past 60 years.