It feels more like 90%+ from my experience of fighting against and behind fences. If you're hit through a fence in a spot that would normally kill you then it should kill you still. But that isn't what's happening. The results speak for themselves. A shot at someone through a fence at greater range than a few rods is a wasted shot in WoR. The reality should be that most of the bullets properly put onto players behind fences should be finding their mark. 50% would be a generous protection, depending on the quality of the fence. A hit square on a rail might stop but at the edges there's little chance it won't chew through and be insufficiently redirected to land more-or-less where it was going in the first place for the next 1-2 feet of travel. I'm not aware of too many accounts where a fence was considered serious protection that fights revolve around. They're mostly an obstacle. I wouldn't feel the least bit safe standing behind one. Safer than in the open but not much at all.
You can't tell me that the .58 caliber minie ball, even ricocheting off a fence isn't going to do more damage than the pistolball ammunition, which almost always drops people in one shot in WoR. A slight deviation in trajectory isn't going to result in just a slight wound more often than not.
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