If someone in the 18th century didn't have the freedom to amass a collection of cannon for his frigate, how would he carry out a Letter of Marque, as authorized in the US Constitution, Article I, Section 8?
I think that in the 18th Century, the arming of ships was commonly done for defense against pirates and because they could be issued Letters of Marque. From what Scalia said and how I’ve always understood the First Amendment, it referred to individual persons having the right to own guns, because all the men of a community were considered to be members of the miltia for the defense of the community.
And it was an armed citizenry that the royal governments were afraid of, the people having the capability to defend themselves from an oppressive government. Some local communities has cannons as part of their militia organization but the key, in my view, was to ensure that the individual person had the right to own firearms.