If you were in process on fine-tuning - that might need revisiting for the new powder.

As for the quality of Goex, my experience has been that it's a great powder.
I've gone through development of regulation loads for a handful of blackpowder bore-rifles, as well as load development for quite a few percussion rifles. Running over the chronograph, looking at fouling and studying patches and the results on the targets, Goex has grown to be my favorite powder -- even when (in all cases but one rifle) compared to Swiss brand powder.

That all and the price is right and it's easy to get.

Is this a hunting rifle?

Cheers
Tinker