Welp, there ya have it. I build my flintlocks using no brass. So, I assume if I’m building a rifle/pistol and use brass (butt plate, patch box, trigger guard) I need brass screws.
So after looking at several “brassy” builds more closely, I see steel screws are used.
So there ya have it. I’m going to build a rifle using more brass than ever. But I see that steel screws are correct.
I learn all kinds of things here.