Sparky or barrelguy
Give me the spring spec. you think will work
I think I can get it sampled out
The graingers link I posted has all the specs. I used the one posted, .038 wire, there is also .042 and .045 which have much higher ratings.
My primer strikes look good, maybe a touch on the light side BUT they detonate just fine. That being said.... spring selection is going to vary by individual firing pin design, the weight of the pin has a effect as does its travel along with the spring. Preload on the spring makes a BIG difference too. (this is more for others than Cutter, he has experimented with springs in depth before)
Google searching the other day, I found info that said 20-23 lbs spring rate for center fires was common. My pins are .062 dia, commercial rifles are either .062 or .078 dia from what I seen. (guys dont seem to like the .078, many reworked to .062)
Another triva point..... clearance of the pin tip to its hole.... .002 to .006 is the common range that seems to present no problems. (this is on rifle cartridges that have MUCH higher pressure than the 357 so its quite safe for the 357)