I first learned Springmaking from Roy Dunlap's book Gunsmithing many uears ago. As Hammergun said its not really that difficult & have successfully made a good many over the years. My heat treat "Furnace" was a propane torch, watching the colors. As Dunlap said once you have it made put it in a vice & squeeze it shut, if its too soft it will not spring back & needs re-heattreating. On the other hand if its too hard, Start Over, that one just broke.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra