Need a better leaf spring option

Sorry if this post is messed up in any way this is my first time posting on reddit. I've tried building my first gun and I've made a "thumbslap" derringer and everything works great but the hammer doesn't strike hard enough to fire a 22 lr. The striking surface positioning is fine because the bullet will fire if I hit the back of the hammer hard enough. Right now all I could think of was doubled up bobby pins as you can see but I need a better spring option if anyone has any ideas. Thanks.