Bill Hanus was a big fan of #9 for pheasant and other birds inside of 30 yards. Claims the sectional density "shock" kills them and the small pellets would penetrate head and neck while not penetrating feathers into the body. Charles "Nick" Hammack who developed the DR16 wad with Kevin at Downrange also says the same thing for phez in SD. They both claim light loads of 9 shot at high velocity do the trick best. Personally I want an oz. and a quarter of #5 @1200 fps on my November and later pheasants in SD. Bird numbers aren't what they used to be and only have so many days to hunt. I'm not going to pass on shooting at a bird that is "out of range" because I brought a knife to a gunfight. The dogs work too hard for that to happen.
Not a fan of 9 shot for either feathers or clays.
Stan, regarding downrange energy and depth of penetration with 9's...
I used to shoot Skeet with both 8's an d 9's but in the colder months the 9's just didn't have it every time I hit a clay. I don't know if the clay targets get harder in the cold or if the powder didn't have enough oomph because of the cold, but I never had that problem with 8's.
I've never used 9's for hunting and I gave up shooting it entirely back then when I had poor results at Skeet.
I'm with you and yes cold makes a difference. Not only harder but the targets that sit through freeze and thaw cycles get "punky" as they absorb moisture on the thaw cycle and 9 shot will go through them without breaking them. I went to 8 shot for skeet after my first couple of years in Mn. Even for 16 yard trap in the winter 8's will often just get dust off clays in the winter but 7.5 will break them. When I was younger and dumber used to shoot in the blizzard league against Wi. starting with the Red Eye shoot on Jan. 1 Temps are often in the twenties below zero, Fahrenheit, and you can tell the shooters that are using 8's they will get dust off a target but not break it occasionally. If they were from Mn. I would tell them if they were using 7.5 they would have broken that bird. If they were from Wi. I'd just smile. Actually we all are pretty good friends and the discussion about 7.5 vs. 8 in the winter is common. In the clubhouse with the heater cranked full blast.
Only use I have for 9 shot is to use it for sound and vibration isolation between my Polk towers and Velodyne subwoofers.
I also have 4 bags of 9 shot in the base of the printer stand that the swing arm monitor is connected to next to me to stabilize it. About the only thing I can think of where 9 shot is useful. Paid less than $10 a bag for it back then, now I have a small fortune in 9 shot ballast in my living room.