Question about Colonial Shur Snap fishtail

[#goldpan]

I just picked one up. However the butt spring is missing. Curiously it does not look to have ever had one. The pin holes in the liner look like they were never used. Here are some photos. Hope someone can help with info on the butt spring. I'm sure I can make one but would like to get a better idea on how it looks and is mounted in the frame before I take it apart and start the process of trial and error!

Randy

[knife7knut]

The spring has a slight U shape where it goes under the projection(or in some the center spine rivet). I have made temporary ones from old large hair pins and they work for a bit but lose tension quickly. I have a couple of those that have slightly different blade grinds.