Now, that does not mean that an unprotected right may never be infringed. Congress may reasonably regulate fundamental rights.
If Congress wishes to constitutionally regulate the interstate commerce of particular weapons due to a compelling state interest,they have only the people to answer to.
That doesn’t answer the question. If Congress can “constitutionally regulate the interstate commerce of particular weapons”, what prevents them from incrementally regulating out of existence the ability to obtain or own any kind of firearm at all? According to you, nothing in the Constitution.