There was a tale that when Ripon and Walsingham were on adjacent pegs a covey of 8 partridge went over and all were bagged. I have seen, on a number of times, 4 pheasant dead in the air at the same time to one Gun (shooter) with a pair of guns and a loader. My old boss, now deceased, once shot 99 pheasant on just one drive and was a bit disappointed when the whistle went without him making it an even 100.
These double gun teams would put in alot of dry practice and work like a well oiled machine. Seven is pushing it a bit unless killing more than one at a shot. Five, just about feasible in my opinion. Lagopus.....