Each time I stretched the spring to the specified length and then squished it down completely, as the resting length after stretching was a little longer than the resting length after squishing it down. Compressing the spring completely seemed to make the resting length more stable.
After I got the resting length I wanted, I put them in the toaster at 325° for 2 hours, then let them cool slowly in the toaster.
|to get:||stretch to:|
Don't take these as gospel. This is what worked for me, it should give you an idea of how far you need to stretch the spring. I was really surprised how far I had to pull them to get them to change resting size. 44" is more than 3-1/2 feet, and it takes a surprising amount of force.
Also, it seems to matter quite a bunch how many coils you grab to hold on when you're stretching. if you grab only one coil or just the end of the spring wire you'll have to stretch farther, if you grab 2 or 3 coils, you won't have to stretch as far.