Remove the hop unit from the gun
Remove the barrel and bucking
Install a flat hop bucking or modify a standard bucking for flat hop
Trim the bucking contact mound to a flat surface
Install a flat hop nub or a properly shaped spacer
Clean the barrel thoroughly
Align the bucking and barrel window correctly
Reassemble the hop unit
Set the hop adjustment to zero
Test with BBs and increase hop gradually
Fine-tune nub pressure for consistent backspin
Check for air seal and feeding issues
Adjust the barrel, bucking, or nub if needed