1. Cut off old hole 2. Clamp the spring in a vise for a heat-sink. Anneal a couple of inches of the end of the spring. Heat to cherry red, then withdraw flame slowly. If it cools too fast it may air-harden. Let it cool on its own; don't quench it. After annealing. 3. Round the end of the spring. 4. Center punch the location for the hole. 5. Drill the hole. 6. Re-shape the hole with a Dremel. As you can see, I use a flex shaft, diamond bit. 7. Re-shaped hole should look something like this. 8. Make a sharp, straight bend at the front edge of the hole. The corner of the bend —and therefore the front edge of the hole— will press against the inside of the barrel, making it easier for the barrel hook to grab it. 9. The final product.