Share A bronze cannon recently recovered by researchers in Arizona appears to be the oldest known firearm ever found in the continental United States. According to experts, analysis indicates the 40 lbs weapon was likely owned by one of history’s most famous and notorious conquistadors, although he may never have fired it in battle. Get the Popular Science newsletter Breakthroughs, discoveries, and DIY tips sent every weekday. Email address Sign up Thank you! By signing up you agree to our Terms of Service and Privacy Policy. In 1539, Vázquez de…