Post · September 17, 2025
What a little more than half a day of neck fitting a 10M can look like. The left most picture is after everything was cleaned and the initial expansion was done and the first lapping step was done and then the lapping compound cleaned away. You can see the (typical) low spots below and around the neck screw slot in the dull metal.
This is typically caused by overtightening of the neck screw, a problem that typically starts with a loose neck, possibly from a slight pulldown or just time or a bad fit from the factory. The top of the receiver gets tightened too much and ovals out and creates a bulge beneath the slot, and it gets worse over time. In the case of the 10M, I think sometimes this is also caused by the metal end plug tap tap tapping away at the receiver as the horn jostles in its case, and that receiver on the 10M is underbuilt already.