Problem:
https://youtu.be/cT6dwaOpZkc?si=uwThuBCDvYlPWaiR

Details: New to me gun, clean barrel.
Pydrodex powder about 85 grains.
Traditions TPF hunter sabot, 245 grains.
I have the slightly older ones that look like hollow points.

Pan powder 4F.
Took 6 shots, all had excessive burn time.

Solutions:
Bad 4F powder?
Use 3F instead of pyrodex?
Issues with peep hole?

Thanks for your recommendation.