I ran some tests for accuracy and velocity using T7 in my 40-70 Shiloh Sharps # 1 Sporter with MVA tang and front sights. All shooting was done from a bench. It is indeed a more powerful powder than the real stuff but in my particular rifle and one bullet it was not as accurate as black. It certainly had enough accuracy for hunting but for me I wouldn't want to shoot a match with it in that rifle with that bullet. Fouling was negligible If I couldn't get black I'd be using T7.
Vic