This is the problem. When it comes to abortion, there's a notable portion of the populace (including Supreme Court Justices) that say "well it doesn't literally and explicitly call that out in the Consitution so no, it's not a guaranteed right".

... then when it comes to guns... "Well, of course it includes _purchasing_ those arms, even if it doesn't explicitly and literally say so, because it'd be hard to bear them otherwise, so it somehow _must_ guarantee that, too!"