I agree with Jim that the patch box for this rifle should be a little shorter. The patch box used on the original rifle that Jim based his kit on is only 5 1/2" total in length. It is also rounded on the ends, most people tend to want to use the more tapered and pointed ends on these patch boxes which I agree look better. I would also move the box a little more toward the butt plate.
I use cut nails to make the catch and old hack saw blades to make the lid spring. The cut nail can be forged out to shape using a propane torch or Mapp gas and the anvil on your vise, I just draw the nail out pretty thin the file the shank to the shape I want and file the head to shape then heat it to a bright yellow orange and quench in transmission fluid. I then polish bright and draw it back to a purple blue color. This should give a nice spring to the catch that is tuff enough to drive into the sock to keep the catch in place. Some people like to put a bend at the bottom of the catch and attach it to the bottom of the box cavity with a screw. I have seen it done both ways on originals so either would be correct.
The lid spring I make out of old hack saw blades. I grind them to shape on my bench grinder, shape it using a Mapp torch for heat and make my bends in the spring while at a bright orange temp. I then heat the spring once I have it shaped and the mounting hole drilled to a bright orange and quench in transmission fluid. I then polish it bright and temper back to the purple blue color. Good luck with your project.
