It's a small 1-2mm gap, but it didn't start with Set 5. I completed Set 4, 3 and 2 with a 1mm gap or less. I just tried all five Sets to see how they fit. Sets 2, 3, 4 and 5 all feel loose though they did not fully track. HOWEVER, my very first set still fits tightly!! With Set 1 the tracking is slightly off. Should I start back with Set 1 and use chewies to get them to track fully before moving to a new set? That seems logical to me.