T-7 has the same "active ingredient" as P-dex does according to my friend who is an acknowledged expert in the field.
It is covered by the same patent or so I am told.
It is less active than Pyrodex but will do the same thing only in a little longer time frame.
Leaving a gun 2 weeks with BP will cause "frosting", micro pit, if the humidity is over 30% and might even do it at less RH if left that long. I cannot imagine T-7 doing any less.
The thing one must remember is that the stuff does not have to create red rust to cause damage so finding no rust is not a sign there is no damage.

Dan