Calibration should have been the first step before printing anything. Every printer needs to be calibrated. Every filament needs to be calibrated.

20mm cube is too small plus 100mm makes it much easier. If it comes out to 99.88mm then shrinkage is 99.88 in orca.

Pa6 should be measured after annealing and moisture conditioning. Annealing can cause it to shrink but moisture can cause it to expand.

This is py2a 500 not fossberg. The prong nut is an odd choice for what they are using to hold the ejector screw on. There are remixes of the normal recievers and the fossberg use a standard nut or square nut. I dont think I saw one for the space trench.