I recall meeting Gene Hill many years back at the Iowa Governor's Pheasant Hunt. Chatting with him after lunch, I asked him the hammergun question, knowing that he hunted with them from time to time. In my case, I'd started with a hammer single, which isn't the easiest thing for a kid to cock, especially on a cold day with gloves on. But we never cocked those until the bird was in the air. Hill said he carried his hammerguns loaded, cocked, and open. Hunting something like prairie grouse, where cover is typically shin high, I think that can work. But the problem of stress on the gun aside, clearly if you're hunting grouse and woodcock, or even pheasants in heavier cover, what's likely to happen is that you're going to get some crud in your gun and you'll find that it won't close when you want it to.
