I have wounded one, but was lucky enough to finish the job.
Watched him come in from over a mile away and he was coming into range like he was on a string. Problem is, he was moving at a decent pace, and once he got inside about 400 yards he was going to be in some really thick juniper and sage that would provide extremely limited views of him until he inevitably disappeared completely. It was either going to be a long shot or very likely no shot.
I ranged several trees, rocks, and bushes between 400 and 425 yards away so I knew that if he walked through any given gap I had picked out he would be in that window. I referenced my drop chart to see how high I needed to hold my rifle, a Remington 700 in 7mag with a Wal-Mart Simmons scope (duplex reticle). A hand me down from the grandfather that introduced me to elk hunting, and even though I knew this setup was limiting my capabilities significantly I was determined to kill an elk with it. I had only shot that rifle at >400 yards once or twice but I did at least know my chart was going to put me in minute-of-elk-vitals if I got the holdover right.
Sure enough he had slowed his pace to a slow walk and was coming in to one of the gaps I had ranged, though he wasn't going to stop walking. I picked the spot where I'd shoot, estimated my hold, squeezed off a round, and watched him take off into the thicket that could have prevented me from ever seeing him again. Thankfully he didn't change directions, and as I caught glimpses of him between junipers getting closer and closer to me I could tell he was injured, but now he was definitely trying to get out of dodge, not just taking a stroll.
He was now well into "hit where you aim" range so I wasn't worried about a holdover anymore, just getting the reticle on him again. He was headed towards a small clearing where I would have probably 4-6 wounded elk strides to shoot him before he disappeared completely into a nasty, deep ravine. Almost exactly 100 yards in front of my position on the ridge. I setup, swung with him like I was wing shooting, and fired again just before he dropped off into the ravine. I lost sight of him immediately, but it was one of those where it felt like he fell out of my sight picture, not that recoil had me looking somewhere else. Everything was silent, and had he still been running I should have definitely heard it.
I packed up and tried to calm myself down, walked down the ridge, and found him dead about one stride past where I took the second shot. There were tracks and blood in one place, and a dead bull just over the edge of the ravine...thankfully he hadn't tumbled all the way down. The first shot hit nothing but meat and bone high in the front leg...just a few inches low of going into the chest cavity when it passed through. The second shot was through his heart.
Took the lesson from those extremely tense minutes about picking a shot, choosing a shot, and letting them live when the situation isn't perfect. Upgraded my rifle, scope, and shooting out to 500 yards before the next season so I could be a lot more confident in the future. Between better equipment, better skills, and better decision making, I haven't had any more close calls or oopsies since then.