Stan: It's the one that goes out straight away in about the center of the field and is moving fast without much obvious change in elevation at first. So I cannot figure out if it an optical illusion, maybe even climbing a little. I think I have tried about every possible approach to that one but I don't connect very often. Any thoughts would be most welcome!
Are you saying the trap is situated in the center of the field in front of you, and how far away from you is the trap? If so, do you only miss it from station 3, which is the only station that it would be a true straightaway? On stations 1,2,4 and 5 it would be a quartering way target, in two different degrees. Also, in how much upward arc does the target travel? It has to go upwards to some degree to keep shooters from shooting the trap itself. I'm trying to picture the presentation.
If it is a true straightaway, and not quartering in the least, there are at least two scenarios.
IF you're on line left to right you're shooting ahead of it, or you're shooting behind it.
Many times, with these slightly rising straightaways, the target setter will set the trap so that you see the bird rising upwards slightly so you put some forward allowance on it, only to end up shooting in front of it. Why? Because by the time your mind sees the lead and you shoot, and the shot swarm gets there, the target has peaked and is no longer climbing. Very often these presentations call for shooting straight at it.
Another possibility is that it's climbing for a longer length of time than you realize and you're not putting enough forward allowance on it. On presentations like these I start my gun behind the bird and move the gun faster than the bird is climbing, pulling through it and firing as i pass it, with a definite follow through, keeping the gun moving even after I've fired. Stopping the gun when firing is a very common fault with these kinds of presentations. Make sure you're not doing that by having someone watch you from behind.