Comment by Terr_

> it must have been the case that captains had these types of weapons.

Some did, but that doesn't mean states couldn't (or didn't) have laws touching on it.

Similarly, I own and use a car today... but that doesn't mean "the state can't have safety requirements for vehicles", nor does it mean "the state can't bar a legally-blind 20-time DUI convict from driving."

> your analogy

I have a much better/closer one to offer. Consider that tomorrow the Federal legislature could grant a letter of Marque and Reprisal to someone who... Is a convicted murderer held on (state) death-row.

Does that possible wrinkle mean the original Constitution actually banned States from running their own prison systems all along? Does it mean only the federal government is allowed to sentence anybody to carceral punishment?

Obviously not, that'd be an insane conclusion... Yet the only difference here which realm of state law was "getting in the way." If a state can't have gun control because of an M&R letter, then it can't have prisons either.