Flint leather way too thick. Cut new ones from an old wallet , tongue of old shoe , or of thin leather like those examples. Take a 3 corner file , and put grooves in the hammer jaws. Take a hack saw and deepen the screw driver slot a few thousandths for more robust screwdriver. Always lubricate the threads on the jaw screw to eliminate thread friction. You should only have to tighten a flint in the jaws after several dozen shots , or maybe never. Do these suggestions , and you'll be a regular "flint hammer mechanic". Just think of the glory of it!! Others will be knocking on your door wanting this knowledge. My emoji's were taken away , or I would have embellished this post w/ some.