Yes.
I couldn't justify buying a $30lb can of FFFFg to prime with. I only own one flint lock. And am already 34 years old.
Its a bit slower (more delay) but it works fine for me.
I actually bought a pan priming flask so I set to work with small amounts of FFF and a stone mortar and pestle and carefully, gingerly broke the granules down a bit....but when I ran out I didn't bother doing that again I just started using FFFg.