Not really comparative experience, but I use t-7 because I have read that the Pyrodex flavors are more corrosive, and so never tried them. Of course, everything that burns in a ML is corrosive, so there is no magic powder. T-7 just has a reputation of being less so. Shoots extremely well in my rifles. And packs a punch that Cowboy noted with his correct 15% reduction conversion for t-7 that should not be ignored. Still measured by volume like BP. It burns fairly clean compared to BP I have used, but it does leave a 'crud ring' at the chamber that is best swiped out between shots. SW
Maybe a humidity problem we don't really have here in MT, Rawhide. I just killed two does with t-7, 2f that was left in my flask for a year. And I've been experimenting with the 3f for 3 years. Some from a flask and some from an open container. I am keeping an eye on them both though, because it would be foolish to entirely discount your experience. Maybe it's not operative here, or maybe it will take longer. By hook or crook, I will find out. Hopefully before pulling the trigger on a deer. Pre-season practice should tip me off to a problem SW