For some strange reason, this excellent thread has devolved into a discussion about all kinds of hunting and target shooting.
I would like to return to the original question. Upland hunting is my passion. I shoot international trap for something to do in the summer, but I live for the uplands.
Having said that, not all uplands are created equally. Bobwhite, ruffed grouse, and Hungarian partridge are delicate birds compared to some. Sharptail and pheasant are examples of surprisingly tough species. Some upland habitats support both delicate and tough species. In others, you're effectively hunting only one species at a time.
If an individual is hunting only what I'm calling delicate species (for the sake of this discussion), one should consider the classic British bird gun. By "classic", I'm referring to a double gun equipped with double triggers, straight stock, well balanced, and weighing appropriately to the gauge (in the 6 lb range for a 12 gauge). I would further suggest that the ideal load for this purpose would be a low pressure, light load, such as Gamebore Pure Gold from the UK (available from your local Kent Cartridge dealer in Canada).
The choke selection for this gun could be IMP. CYL/MOD for thick cover or early season hunts, and FULL/MOD for hunting more open land and late season hunts. Aside from the obvious benefits of using Gamebore loads, such as reduced recoil and compatibility with 2 1/2" chambered guns, these loads employ fibre wads - a nod to our heritage as custodians of the forest, but more importantly, leaving the chokes to do their job. (plastic shot cups - ptui!!)
I would argue that the gun to use on the tough species is a different gun. It could still be a double, and it could surely still be well balanced, but it will need to be a bit on the heavy side. The extra weight (1 to 1 1/2 lbs more in the case of 12 ga.) helps offset the heavier loads needed to cleanly dispatch these species and is mostly from the more robust lockup on the receiver. For these birds, I use 1 oz of 6-shot in the more open barrel and 1 1/4 to 1 1/2 oz of 4-shot in the tighter barrel. These are typically old lead shot loads for migratory birds that we used to use in the good old days. NOTE: I recommend always double guns in the uplands, so you have a choice of chokes. Naturally, you only benefit from this choice if the barrels are individually triggered.
Regardless of what upland species I hunt, I don't use a .22. As far as I'm concerned, it's child's play to aim a full choked barrel at a stationary bird and take it's head off cleanly, without putting a single pellet in the body. This only applies out to about 25 yards. Beyond the 25 yds, I would approach the bird, ready for a wing shot; or a closer stationary shot, if the bird doesn't budge. I hunt with a dog, so I pass on ground shots, just to be safe. When presented with a ground shot, I simply turn it into a wing shot or a tree shot - it's up to the bird.
Given a choice, a wing shot on a hidden bird suddenly busting cover is what I want. I find these are the most challenging and, therefore, the most satisfying.
All of the above applies to 16 an 20 ga. equally, except that the ideal weights have to be scaled down, too. Gamebore makes low pressure, 2 1/2" shells for 16 and 20, only they brand those as "Traditional Game".