would this "sweet spot" change when changing powders? or will it always be at that length? this should carry over to all bullets right?
The cause of seating depth affects is as big of a mystery to me as anything in reloading.
The affects are huge though, I know that.
Like Greyfox, I have not seen powder influence a sweet spot in seating. That is, neither powder type, nor amount. But changing bullets definitely changes things.
Sometimes you remain near the sweet spot with a bullet change, but this is more coincidence than basis for expecting it.
It is mind boggling to me that so many reloaders assume jam, or any other setting is best, and don't even bother to find otherwise..