It's a pretty safe bet that neither candidate would violate the official 2012 platform of their respective parties.
Following are the official platforms of the two parties relative to the Second Amendment.
It's pretty clear which candidate any supporter of the Second Amendment should prefer.
The Second Amendment: Our Right to Keep and Bear Arms
We uphold the right of individuals to keep and bear arms, a right which antedated the Constitution and was solemnly confirmed by the Second Amendment. We acknowledge, support, and defend the law-abiding citizen’s God-given right of self-defense. We call for the protection of such fundamental individual rights recognized in the Supreme Court’s decisions in District of Columbia v. Heller and McDonald v. Chicago affirming that right, and we recognize the individual responsibility to safely use and store firearms. This also includes the right to obtain and store ammunition without registration. We support the fundamental right to self-defense wherever a law-abiding citizen has a legal right to be, and we support federal legislation that would expand the exercise of that right by allowing those with state-issued carry permits to carry firearms in any state that issues such permits to its own residents. Gun ownership is responsible citizenship, enabling Americans to defend their homes and communities. We condemn frivolous lawsuits against gun manufacturers and oppose federal licensing or registration of law-abiding gun owners. We oppose legislation that is intended to restrict our Second Amendment rights by limiting the capacity of clips or magazines or otherwise restoring the ill-considered Clinton gun ban. We condemn the reckless actions associated with the operation known as “Fast and Furious,” conducted by the Department of Justice, which resulted in the murder of a U.S. Border Patrol Agent and others on both sides of the border. We applaud the Members of the U.S. House of Representatives in holding the current Administration’s Attorney General in contempt of Congress for his refusal to cooperate with their investigation into that debacle.
We oppose the improper collection of firearms sales information in the four southern border states, which was imposed without congressional authority.
Firearms. We recognize that the individual right to bear arms is an important part of the American tradition, and we will preserve Americans' Second Amendment right to own and use firearms. We believe that the right to own firearms is subject to reasonable regulation. We understand the terrible consequences of gun violence; it serves as a reminder that life is fragile, and our time here is limited and precious. We believe in an honest, open national conversation about firearms. We can focus on effective enforcement of existing laws, especially strengthening our background check system, and we can work together to enact commonsense improvements—like reinstating the assault weapons ban and closing the gun show loophole—so that guns do not fall into the hands of those irresponsible, law-breaking few.