Some great responses and advice, many thanks.
Have adjusted the WTC and it is hugely better now. I'm going to try the Bushnell at HFT on Sunday and see how I get on ... have also tuned it a bit but will do some further plinking + setting on the range before I (what I laughingly call) "compete".
AA TX200, HFT 500, AS400 .22
Daystate Grand Prix & Mk3
Parker-Hale/PAX Phoenix Mk2: .22 & .177