To knock down pheasants you might try # 5's. I have an over under so I use two shot sizes and two chokes( mod and full)I shoot 6 then 5( or 5 then 4 later in the season) for pheasants or 7 1/2 then 6 for chukar and quail. I have switched to high velocity buffered copper plated. Other guys here have used smaller loads. This will give denser shot patterns. How far were you shooting when the roosters got away. I have started using Federal's new Praire Storm shells. ( Anyone else tried these?)They come in 4, 5, and 6 shot sizes. They are high velocity and have special shapped pellets. You can check them out on the federal website. I have knocked down a pheasant at 40 yards and killed it where it fell. The special pellets actually drag a wide long line of feathers into the bird. I was impressed. Hard to find these shells here in seattle(I'm hunting with lead shot on the east side). Only found one store carries them. I even called around a little to try to find them closer. good luck. Do you shoot trap too? Also, have you patterned your gun?