New one is 3/4" wide at the hammer, tapers to 1/2".
Old one below.
Old one was 1/2" wide made from original spring, it cracked at the narrow.
The new one is annealed 1075 spring steel.
Heated and quenched in 140 degree vegetable oil. [After heat treat, the spring was to hard to file, perfect!]
Then into the toaster oven for two hours at 400, the for good measure an other hour at 450. Wrapped in tin foil after polishing.
Also have the spring plunger added for the trigger return.
And, am shooting musket caps.