Democrats in Congress are proposing legislation that would impose a $10,000 fine on gun owners without a "qualified liability insurance policy." California is mulling a variety of taxes and regulations on ammunition. Connecticut legislators have agreed on sweeping legislation that would subject legitimate gun owners to a firearms course, fingerprinting, and a nationwide background check.
Obviously, the goal here is to curb gun violence -- through making the process of becoming a (legal) gun owner as difficult, time-consuming and expensive as possible. The slew of proposed new laws and regulations might even be characterized as "burdensome."
Keep in mind that laws imposing an "undue burden" on fundamental constitutional rights are themselves unconstitutional. And if that standard can be used, as in Planned Parenthood of Southeast Pennsylvania vs. Casey (1992), to scrutinize state laws governing abortion -- a right justices have located in the "penumbra" of the unenumerated right to privacy -- surely the test can (and will) be used to analyze the sweeping gun laws that are now burdening the enumerated right to bear arms guaranteed by the Second Amendment.
Update: Also, how can the left argue that having to show ID (or prove one is a citizen) is an "undue burden" on the right to vote, but all these new rules and regulations do not constitute undue burdens on Second Amendment rights?