Today I was patterning my 870 Super Mag with a factory X-Full choke at 30 yards.  I was using Remington 3 inch Premier Magnum 3 oz 5 shot shells.  It patterned nicely but I was greatly surprised to find one of the shots didn't spread out.  It left a 3 inch hole right where I would want it to, but why wouldn't a random shot spread out?