Tweak on it. What if instead of drilling holes for the spring pins you mill square slots or even angle the slots down some to force the spring to ride to the center? Only reason I mention this tweak is for longer tool life from the spring pins slipping out of the tool when releasing the hammer. Plus the placement may be more forgiving milling vs. drilling. You wouldn’t even need to mill it all the way through, but leave a little meat so the spring pins have a stop on them so the rest of the geometry still works out preventing the hammer from slipping out. Cool tool for sure though.