I also had issues keeping the back stitch lines straight until I started punching holes separately in each piece; the front, welt, and back of the sheath. It’s 3x the amount of punch and mallet work for me but dramatically improved my stitch lines on the back. Ya might give that a try and see if it helps.Really enjoyed seeing this Dennis. Thank you!
One of my big challenges is getting the stitching to come out evenly on the back.
Gotta stay focused on keeping that punch vertical.