No two shotshell patterns are identical. It follows that no two shots on a bird can ever be identical. It isn't even close, for basic wounding ballistics teaches us that there are several types of wounds, for example non-penetrating, penetrating, and perforating.

Distance radically changes the wounding potential of a pellet, and shooting distances vary widely. Bird-bodies are anything but a simple, consistent medium, for penetration varies based on feathers, plumage, skin, fat, soft tissue, air sacs, and bone. The combination varies widely based on the flight path of the bird: passing, going away, rising, incoming, and so forth. There is no way to easily compare a duck flying down into decoys with a wild pheasant that hits the air 30 yards in front of you. The duck is often shot incoming at 25 yards, vitals exposed, the 30 yard flushed pheasant never is.

There never has been a thorough scientific study on wild birds and there likely will not be. You need a control group, and wild birds by nature are not controlled. Observed ranges are mostly anecdotal. It is largely pass / fail. If your bird falls dead, then there is nothing better. If it does not, there is room for improvement somewhere along the line.

Much of the vintage pheasant information stems from pen raised, driven birds, shot incoming and from below. That isn't relevant to wild pheasant hunting. If that wasn't enough, there is the human factor. Was that pattern centered on the bird, and how would you know? Some think a pattern is automatically centered if a bunch of feathers fly, forgetting that feathers are not vital organs.

I have no use for TSS #9. An 80 thousandths wound channel is extremely poor and it has no better strike velocity than #4 lead at 60 yards. TSS #7-1/2 is a far more effective pellet, with an 11% higher strike velocity at 60 yards coupled with better than an 18-1/2 percent larger wound channel. TSS #7-1/2 also has a shorter time of flight, less drop, and less wind drift as well. TSS #7-1/2 also is a markedly better bone-breaker.

Tom Roster defines “long range shotgunning” as anything beyond 45 yards. Mr. Roster goes on to say that “Because of its proclivity for deformation and fragmentation, bismuth shot struggles to produce lethal patterns beyond about 40 yards unless the loads you choose are buffered.” I've only found one bismuth load that gives satisfying 40 yard patterns and that is the current Winchester buffered tin-plated bismuth load.

An often ignored component of shotshell effectiveness is temperature. Above are the KPY ballistics for #4 lead, the same load. What happened? The first data set has a longer time of flight, lower strike velocity, lower energy, and so on. The first shot also has a more open pattern by up to 20%, a bit more drop, and a bit more wind drift as well: yet it is the very same load.

The sole difference is that the uppermost ballistic data is at 32 degrees F., while the second line of data is at 70 degrees F. This should help to explain why your patterns printed on a warm day aren't that great when hunting below freezing temperatures. The pellets and chokes you used are not as effective either. If you generally assess your patterns on more pleasant days, like I do, when hunting conditions are substantially colder than your patterning conditions, it may well make good sense to go from #5 lead to #4, for example, and to tighten your choke by an extra notch of constriction as well.