I suppose you could be right Bager but I have lived all of my 42 years in Arizona and never once have I heard the the term “chaparral” used when referring to the desert vegetation. Although a poor choice I think “shrapnel” may very well have been the intended term.

I’ve lived in Nevada & Utah most of my life (52 years, mostly in rural areas), and many, many of the westerns I’ve read (from Zane Grey’s books written between 1908 & 1939 to modern westerns), and many movies, and many of the people I’ve met – including residents of Arizona & New Mexico – used the term regularly.

My great-grandparents had lived for a time in Arizona, working at a mine near Globe – and my grandparents (on both sides) spent time there before WW2 – and their letters use the term.

Perhaps you simply haven’t met people who use older terms?