After reworking the "genious" chassis design of Challenge - opening the chassis 3(!) holes for free floating the barrel I started considering shiming the barrel. Reason is - while no more temp shifts (proven between 18 to 36 degress) still some sudden poi shifts at 9 and 3 o'clock and then back to zero. It might be the pellets but the barrel seems fits quite loose the chassis - it is simply sloppy when not tightened. And those sharp screws are real pain to tighten the proper and repeatable way. The screws contact spots have nothing in common with the LG110 barrel design and it is a game of chance to align the barrel with the chassis and scope. If I have to summarize: the changes in Challenge design are real ... challenge to overcome and rework to get back the LG110 properties. Just in case: can anybody who has made barrel shiming, give me a practical advise, before I start? I have 0.1mm copper sheet that looks like a good candidate for shiming material. Thank you.