After watching the Veep episode, where the NRA helps Jonah win an election, I wanted to know what the real motivation behind the NRA is. Is it driven by a true belief in the second amendment or are there financial motives also, something similar to the big tobacco lobby for example
The NRA was founded as a marksmanship training organization in 1871. The main motivation of the NRA is education in marksmanship and gun safety. From their mouths:
While widely recognized today as a major political force and as America's foremost defender of Second Amendment rights, the NRA has, since its inception, been the premier firearms education organization in the world. But our successes would not be possible without the tireless efforts and countless hours of service our nearly five million members have given to champion Second Amendment rights and support NRA programs. As former Clinton spokesman George Stephanopoulos said, "Let me make one small vote for the NRA. They're good citizens. They call their congressmen. They write. They vote. They contribute. And they get what they want over time."
Summation: The NRA's mission is the education of the the fundamental principles of marksmanship and firearm safety.
It wasn't until 1975, due to mounting legislative attacks against the freedoms protected by the Second Amendment, that the NRA formed the NRA Institute for Legislative Action. Their mission:
The Institute for Legislative Action (ILA) is the lobbying arm of the NRA. Established in 1975, ILA is committed to preserving the right of all law-abiding individuals to purchase, possess and use firearms for legitimate purposes as guaranteed by the Second Amendment to the U.S. Constitution.
Summation: The mission of the Institute for Legislative Action, a segment of the NRA, is to lobby and organize for the protection of individual liberties and adjacent efforts that support the free exercise of those liberties.
The primary driver of the NRA's political strength is the volume of its membership. Last touted at 4.5 million individuals, this crowd is the motivation that pushes the actions of the NRA, and the tool the NRA uses against politicians. The majority of the members care about the rights protected by the Second Amendment.
The NRA is not "the gun lobby," focused on increasing gun sales, that would be the National Shooting Sports Foundation. This insinuation is an attempt to assign motives to the NRA and the lion's share of their members with the end goal of maligning them and making it more palpable to discard their message.
The NRA is the gun lobby, when defined as "organized group which attempts to influence public policy and law with respect to firearms, especially as an advocate of ownership of and access to firearms by individual citizens", (an apt description).
Lobbying for Unsafe?
There is an accusation that NRA has lobbyied or defended unsafe practices, because they've fought against the requirement that firearms be stored in a manner that unauthorized individuals can't access them (kids, burglars, etc.). The premise of this accusation is true, but the context and motivation behind are being misconstrued. The NRA does not want your kids to have unauthorized access to your firearms (see the Eddie Eagle campaign). In the darkness of our reality, dead kids are bad for public relations. Similarly, your gun being stolen poses a threat to the populace and the efforts to protect Second Amendment rights.
However, the majority of these laws restricting the manner in which you store the firearms require them to be disabled or secured in such away that it is untenable to employ that firearm for your self defense. Look to Washington D.C.'s Firearms Control Regulation Act of 1975, which required firearms in the home to be "unloaded, disassembled, or bound by a trigger lock or similar device." This was found to be a violation of the Second Amendment in DC v. Heller.
In evaluating the accusation that because the NRA receives a sizable portion of its funding through direct contributions from the firearms industry, its focus must be on the health of the same, it is important to understand the difference between First and Second Order effects. When your public goals are expressed as:
“The NRA is the largest and most active firearms rights organization in the world, with four million members who represent 100 million law-abiding Americans who own firearms... American gun owners will never surrender our Second Amendment freedom. Period... Let there be no confusion. Any treaty that includes civilian firearms ownership in its scope will be met with the NRA’s greatest force of opposition.” ~ Wayne La Pierre, speaking before the UN in 2012.
... the First Order effects are the direct purposes of the actions taken to meet that goal. The NRA, in response to outside efforts to drastically curtail or remove the Constitutional protections of the Second Amendment, takes actions to defend the individual right to keep and bear arms from being infringed. The Second Order affects of protecting that individual right, is that the property and accessories that would be legal to purchase, own, and use without the undo influence of external parties, remain so. On the Third order, the businesses that profit of the sale of said items, in the legal market, have in specific interest in maintaining the markets availability.
In 2013, membership dues accounted for 50.5% of the NRA's income. By comparison, the contributions and grants accounted for 27.1%. This is the percentage used to express the influence of the firearm industry.
Is it driven by a true belief in the second amendment or are there financial motives also
I think it's fair to say both--or at least, there are multiple motivations. The history of the NRA is very clearly one of an enthusiasts' organization in that members joined to help spread the sport/hobby/activity of marksmanship and gun ownership. That objective remains active today.
In the more recent times, they've also become a rather large influencer of US politics (of which the VEEP episode was implying). This isn't necessarily a financial incentive, but rather one of political power (which likely indirectly fiscally benefits the industry, but that's a secondary aspect). There is a common rebuttal that the amount of money the NRA contributes to individual candidates is relatively small, and that is true, but the NRA has great sway indirectly, including:
its own super PAC and 501c4 political organization which can run its own political campaign. The two groups combined spent more than $27 million in the 2014 midterm elections on Senate and Congressional candidates, according to the Center for Responsive Politics. A lot of that money was spent on political advertising on television, radio and digital, and on direct mail.
Much of this can be credited to Wayne LaPierre, an effective lobbyist who took over running the NRA several decades ago.