Francisco has an Orvis Odyssey IV reel, the largest of 4 Odyssey sizes and the one advertised as a “Big Game” model. The spring is stainless wire, but was fatigued and needed replacement. It is a simple shape and so an easy DIY task.
I sent him a bit of the finest wire that I had, .024 inch diameter. But it needed something finer yet.
He bought some finer sizes from McMaster (Spring Back Multipurpose 340 Stainless Steel Wire) and ended up installing .015 inch diameter.
How is it that I am typically using .029 wire for trout reel springs, and he needs much smaller wire for “Big Game”? The answer is of course geometry. I have a greater distance between wire support points and a quite different contact with the pawl.