Early in the season when the birds aren't so wild and so heavily feathered, I use "Heavy Trap Loads" (premium hard shot) w/7 1/2s for the first barrel of a 12 guage double. They fold up roosters just fine at sensible ranges. The second barrel I load with 6s.
In the late season I go to 5s in a 12, 3" 4s in a double 20.
The one objection I have to using smaller shot like 7 1/2s is that they get in my teeth! Larger shot are easier to detect both in cleaning the birds and eating them.
When I've had "complete penetration" in pheasants, it was always with 4s or 5s and resulted in a "two-piece" bird...shot too close, too much caffeine! Looked like I was using a bazooka.
