When my son was in Rocky Mountain Park, a ranger told him the fire there was started by sparks from bullets! Actually it was an electric line. At times the informal shooting areas are closed because of fire danger, but it [would really be cigarettes or such IMO. Remember when rangers and similar were all outdoorsmen (and women)?
I did set a weed on fire once with the patch from a muzzle loader, but put it out right away. That, and maybe someone shooting tracers is the only way I can see shooting starting a fire.
I tried starting tinder with: a .36 cap and ball blank--blew the whole pile away,; and with a primed case with the bullet pulled, and the powder put in tinder, same result. This stuff is for the movies. I don't see any need to use the flint and frizzen any time in the near future, either.