Hello Greybeard,
Nice job on the double set triggers!
Have you tried annealing with your BBQ?
Large diameter steel plumber pipe with end caps putting your spring in the pipe, then slowly cooling down.
It works well.
I prefer charcol BBQ over Gas, but they both work well.
I forgot to mention, if you put silica sand in the pipe it gives a better annealing job ( center spring in center of sand )
You can also throw a steak on too!
Old Ford