Hi. I want to talk about metal guitar riffs in A major. There really aren't that many to be honest, but one that comes to mind is one of the most famous metal songs, Crazy Train, by Ozzy Osbourne. There are a few others as well.
And a thing to keep in mind about metal guitar riffs in A major is, usually they're based on the A power chord at the second fret, which is here, and you'll use your first finger. So that's your foundation for the chord.
You can also throw in a single note. You can throw in other chords, relative chords like, C sharp minor, B minor. You could also play this, which is a D chord, that goes back and forth to A. That's something you would hear KISS do a lot.
But the foundation is almost always this power chord. And it's important to learn the A major scale. Not just all over the neck, but for the sake of playing riffs, it's important to learn it in the open position, which would be this. On descending, you'd get this. And those notes are great for coming up with riffs in A major. So, if I come up with a riff in A major, it might be something like.
Have fun with riffs in A major.