The most radical thing the Black Panthers did was give kids free breakfast
According to this article http://ouleft.sp-mesolite.tilted.net/?page_id=1304 this article from 1978 http://colemantruth.net/kate8.pdf shaped public perception of the Black Panthers.
However, it also points out that Newton didn't launch the Breakfast program until after he decided that there was "little support for Armed Insurrection in the Black Community" and changed strategy.
And from the first article:
> As the Black Panthers drew young blacks to their revolutionary program, the Party became the strongest link between the domestic Black Liberation Struggle and global opponents of American imperialism. The North Vietnamese — at war with the United States — sent letters home to the families of American prisoners of war (POWs) through the Black Panther Party and discussed releasing POWs in exchange for the release of Panthers from U.S. jails. Cuba offered political asylum to Black Panthers and began developing a military training ground for them. Algeria — then the center of Pan-Africanism and a world hub of anti-imperialism that hosted embassies for most postcolonial governments and independence movements — granted the Panthers national diplomatic status and an embassy building of their own, where the Panthers headquartered their International Section under the leadership of Eldridge and Kathleen Cleaver. But by the time of Newton’s trip to China, the Black Panther Party had begun to unravel. In the early 1970s, the Party rapidly declined. By mid-1972, it was basically a local Oakland community organization once again.
Apparently most of the membership weren't really that interested in what they were doing and left.
http://www.vox.com/2016/2/14/10981986/black-panthers-breakfast-beyonce