I had a play with trying to sort the foil trigger today. Getting consistancy of pellet travel is still eluding me. Attached is a graphic that explains the problem.
So confident was I that .... yes another grape shot, but here the pellet had travelled way out of frame so too far. Bits of grape all over the place, and as I am using 55mm macro I had to wash the camera down afterwards. Important to use a filter as this needs cleaning after each shot. I am quite sure this would even apply if a 150mm lens was used as I even had bits of grape on my workshop clock on the wall opposite.
Well tomorrow is another day in which to try and solve the problem.
Don