Robinson's body assualt was ferocious, although I don't know if he ever stopped anyone with a bodyshot.
McGuigan was a very good body puncher. Won quite a few fights with his body assault including his double left hook to valerio nati's body in his european title win and his sickening right hand to the body against the B.T. Express
Tho not a knockout, Eddie Gregory against Marvin Johnson quickly came to mind. Cracked rips; that third round LH to the body shot had my beloved Marvin doing a '*****-street' dance. Leonard's 6th round shot to Hearn's ribs in their initial scrap? Brutal! My late buddy always said THAT was the blow that lost it for Tommy that night.
Arguello dug in some nasty body shots, including some hard uppercuts to the solar plexus. Plus, only so many boxers can say they made their opponent crap their pants with a body shot.
Joe Louis made Schmeling scream in pain from body shots. Ortiz waded in with an old school, relentless body attack, nothing fancy about it: [ame]http://www.youtube.com/watch?v=vliQs7a3J5c[/ame] [ame]http://www.youtube.com/watch?v=qu98_XGz0nQ[/ame] 8:00
I think Ray Robinson's right hook (with an inverted fist, knuckles leading) to the ribs has to be one of the most historically significant and identifiable shots. A real stabbing punch that was especially effective against fighters who were in a crouching position.