The second amendment states, "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
The key words are right at the start, "Well regulated militia. Assuming you believe I shouldn't be able to own a functioning tank and shells or a nuclear device then you agree that arms can be regulated and thus should have no constitutional problem with what the majority of democrats advocate. You can disagree of course but don't bring the constitution into it.
Oddly enough Bill O'Reilly, THE Bill O'Rielly recently made this argument on his show. Can't post links but search you-tube for secular talk, he's in one of the recent thumbnails. Perhaps this is a turning point, perhaps not.