I have seen two fires started with target shooting in the West. First you have to understand that on a typical day in the high desert the humidity is 10%. Second in areas covered in basalt there can be VERY high iron content in the rocks. Third many shooters are using steel jacketed rounds for AK style weapons. If there is cheat grass around on a typical Summer day it will ignite simply by looking at it to hard.
Twenty fires unlikely, but a few I believe it.
“Third many shooters are using steel jacketed rounds for AK style weapons.”
No such thing. There are armor piercing rounds this a steel nose insert surrounded by lead/copper but they are expensive or difficult to buy (cop Killer bullets?), and Russian Mfg ammo usually have steel cartrige cases, but none...none are steel jacketed.
Think about it! How long would a rifle barrel last if you shot steel jacketed bullets through it????.... only a very few rounds before the barrel split or the lands worn completely down....