JOHN BIDWELL says:
It’s often easier to take a straightforward teal just before it reaches the top of its climb, assuming, of course, it’s within range of the gun and whatever choke / cartridge combination you’re using at the time.
Few teal are ever straightforward though and will invariably be angled slightly to the right or left, and up or down. Sometimes a fast teal might even be out of range before, or as, it reaches its zenith so the shot will have to be taken on the way up.
All things being equal, I like to take a teal on the up, because when it’s showing a bit of power its flight will be more consistent and you can use the shot string to better effect achieving crisper breaks.
This isn’t to say that I shoot them quickly – far from it. Basically it means picking a suitable place to hit the target comfortably and adopting the appropriate stance / gun address position.
If you prefer to shoot it at the top remember that it will have lost power and can easily be affected by any wind that’s blowing around above the tree tops. If it starts acting inconsistently at the height of its flight then there will be an increased chance of it being missed.