MARBLEHEAD-A Marblehead man turned his Seawall Street backyard into a makeshift firing range early Sunday morning, awaking residents as he fired gunshots into a pile of snow, police said.Adam Dixey, 28, of 30 Seawall St., was arrested shortly after midnight and charged with discharging a firearm within 500 feet of a dwelling.Police received multiple calls from neighbors reporting gunshots when they zeroed in on Dixey’s home.Investigating officers reported finding 11 rounds from a .9 mm handgun in a pile of snow behind Dixey’s home, police said.According to Marblehead police spokesperson Lt. Dave Millet, when Dixey was asked of a motive to his alleged actions, he replied, “I don’t know.”Police said more charges might be brought against Dixey.