Regarding the T7- I switched from Pyrodex 10 yrs or so ago & truly have had no complaints.
The patches, I've been purchasing pillow ticking by the yard (& recently found two different ones to try), look almost unused after the shot and, truth be told, I've reused more than a few w/no notable change in accuracy.

Again, I'm assuming barrel break-in here of 100 rds before filing the sight at all.