“Private citizens could own cannons in the colonial days. Needed them to protect ships from piracy.”
Absolutely correct. Col. Moultrie, commander of South Carolina’s 1st and 2nd regiments, loaned his cannons to the battalions to defend Charleston Harbor against the British warships in 1776. They dug into Sullivan’s Island in the harbor and blasted the hell out of the British fleet. The result was one of America’s most decisive victories early in our war for independence. Here’s more details:
http://www.carolana.com/SC/Revolution/revolution_ft_moultrie_1.html
IIRC, the British were coming for the Colonials’ cannon.