Jump into it, if a rock even sort of looks like it will make conchoidal fractures, I will try to make a gunflint out of it. If it does and sparks well, I'll make more. Scrounging rocks is part of the fun.
As far as being lucky enough to have access to suitable rocks, well, part of that "luck" is enduring 11 months of summer (I was out shooting today in 106 degree ambient temps with 55% humidity), extreme drought periods (had about five inches of rain to date this year), and general weather misery.
As far as being lucky enough to have access to suitable rocks, well, part of that "luck" is enduring 11 months of summer (I was out shooting today in 106 degree ambient temps with 55% humidity), extreme drought periods (had about five inches of rain to date this year), and general weather misery.