Indeed it is, Mike--including pheasants.
I've often hunted pheasants with a European double equipped with a sling, but the only time I sling arms is after I've shot my last bird, or if I'm getting the gun out of the way to snap a picture. Hunting pheasants--or any other relatively open country bird--while carrying at sling arms can work, if you have a pointing dog and shoot only pointed birds. But I've found that pheasants flush in range, quite frequently, when the dog's nowhere around them. I'm not above shooting unpointed birds under those circumstances.
Snipe (and rail), in my view, fall into a sort of in between category. They're found in or near water, and many states require that hunters use nontoxic shot. For me, that makes them not quite upland, not quite waterfowl.
