Ditto on SCOTUS nominations, not to mention other court appointments. That's probably the most important function (in terms of RKBA) of the Presidency.
In the next 4-8 years it is likely that the SCOTUS will have a couple seats vacated, as Justices Scalia, Kennedy, and Ginsburg are all 75+ years old. 75-80 seems to be a common age for SCOTUS Justice retirement.
It is important to note; the President doesn't appoint Justices to the SCOTUS, they are nominated. SCOTUS nominees must be confirmed by the Senate. Without straying too far into partisan politics, obtaining a conservative majority in the Senate* is just as important as winning the Presidency.
* Pro-2ndA mindsets are more prevalent among conservative politicians vice liberal politicians. Therefore, the argument can be made that a conservative majority in the Senate is more favorable towards gun owners. I acknowledge that there are liberal politicians and individuals which are pro-2ndA, however they are the exception, not the rule.
"To preserve liberty, it is essential that the whole body of the people always possess arms, and be taught alike, especially when young, how to use them." -Richard Henry Lee, Virginia delegate to the Continental Congress, initiator of the Declaration of Independence, and member of the first Senate, which passed the Bill of Rights.