Rising teal are a tough target for me. The target is rising but losing velocity very quickly. I've tried swinging through and blotting out the target with limited success. Either I stop the gun or I shoot over.
I have had this experience as well. Because the teal is loosing speed and I am coming from behind, I have a tendency to move my gun too fast and over swing with the swing through method. Sometimes I stop when I loose track of the target. That is the reason for my caution in my first post. That said, I really like the wing through method on very close presentations, but I find that those target setters are not very accommodating in giving me stuff that I shoot well. What works best for me on the longer stuff is reminding myself not to rush my shot and not to let the teal get in front of my gun as this forces me to recover by the swing through method which does not work well for me. Hmm, I htink I just said that?

I pick my spot where I want to make my break and position my gun well above where I will first clearly see the target. I try to look through or around my gun (I am not sure how this works but it does for me) and slowly mount and shoot without causing any jerking motion. I make a calm effort to start and stay in front of the teal but do not try to calculate any specific lead. If I stick to this plan and I trust my gun mount and pointing ability I usually do well. I do not think that this is an exact science, but sometimes, and you will know the time, just spot shoot them at the peak and as CB says blow their tiny little feet off.
If one or two of these targets didn't drive me crazy I would not be crazy enought to keep comming back