Don't know, two clips would be mighty excessive, especialy considering you'd be doing real well to get a couple/three shots off, the rest would just be reckless endangerment of anybody downrange. :) Suggest using something with more power, M1A or other .308 would be best, AK/SKS would be OK as would AR-15 or other .223. Even a 12 gauge, with 9-12 pellets of 00 Buck per shot would be a better choice. In fact since shotguns are designed for shooting at flying targets, this would seem ideal. Never mind Patton shooting down that Nazi airplane with his 1911, you'd be better off with a shoulder fired weapon.