Good post, Tom - I wasn't sure about T-7's properties other than it's problems with heavier loads in my .69.

I am told that BP fouling itself is not corrosive - it needs to absorb moisture, then becomes an ozidizer, whereas the percholates are, without the addition of water (iirc). BP fouling actually needs water or moisture absorbtion and only become an oxidizer if the humidity is in excess of 35% whereas the addition of any moisture strengthens the acidic nature of percholate powders. I'm just repeating what I've gleaned from other sources.
I have read that T7 is not as bad in this regards as-is Pyrodex. Too, due to it's own chemical nature, T-7 is longer lasting than Pyrodex once opened, whereas pyro loses power rather quickly incomparison.

My own tests have shown BP fouling is not an oxidizer without the absorbsion of moisture. Kept at an ambient humidity of 30%, there was no oxidation to the surface of the metal over a 7 day period, but there was minor colour change from clean and shiny, where-as Pyrodex etched the surface quite evenly, end to end of the test material under the same conditions. Hardly Lab oriented, but useful just the same. I flushed all the pyrodex I had at that time.