Never said it was silent from the guide gun, said the load is a supposedly silent 45-70 load. Anyway, your post made me go back and check the exact language of the article. To my horror, I realized that it didn't mention Bullseye in the 45-70, it mentions Bullseye under Black Powder for the 45-90. He also mentions a silent load using Bullseye in the 6.5x55mm. I think that is what I was thinking about.
Here's the article if you're interested:
http://www.sixgunner.com/paco/pprofile11.htm
Sorry for the confusion,
Chris