Uncle Sam's 14-inch railway rifle, billed as the largest piece of mobile artillery in existence, fires its first battle practice round from the heights of Fort MacArthur, San Pedro, California, in 1927. Operated by Battery B, 3rd Regiment, U.S. Coast Artillery, the massive gun could hurl nearly a ton of steel over fifteen miles, embodying the Army's interwar strategy of railway-mounted mobile coastal defense. Project: 218645