Hi fellas. Thanks for all your thoughtful responses. Since posting this, I have found that the threads in the mechanism that takes the silver screw adjuster you see at the trigger were duff; not the screw itself. So that decides the remedy! This was a restoration of a second-hand HW80K I've taken from a rusted, worn-out wreck to a polished, Good-as-New, full power, match-accurate hunter and the previous owner was not the most subtle -or knowledgeable of handlers, shall we say! Getting the trigger unit re-blued and set right is the last stage of my work on it and, I'm not taking chances on safe