Im going to give a shout out to Bill Squires who seemed to have nothing BUT a muderous punch. In his time he was quite a beast, but for whatever reason never seemed to be able to grasp the finer details of boxing. He would have been quite a hand full under prize ring rules a couple of decades earlier.
Julian Jackson is a lock for this imo. Another terrific puncher though was Maxy Baer. I know he goofed around a lot and had some sloppy skills but for raw concussive power he's right up there. Some of his KO's were brutal. I recall an older Baer flattening Pat Comiskey (I think his name was) with a single right hand and even though the film quality was poor you still got a feel for how hard a shot it was. He badly hurt more than one opponent.
I never could understand Julian Jackson's power as much as say John Mugabi, who had just physical force. I always said that Jackson was not a limited boxer because if you look at it, the punch he landed on Norris was clean enough that even if he was not a big puncher it would have hurt Terry. He landed a clean perfect punch. On Drayton ext. Somehow Julian punched as though he had a cast on his hand and arm and body when he would land, and he knew how to put his whole body into the punch as he tightened it up so the whole body was the punch and turn with it, better than anyone else I have seen. Another guy my favorite Thomas Hearns knew also, but Tommy used more speed and leverage. Hearns would jab and bust up guys and soften them and then land his right and end it, but Jackson could end it without the softening. And Mugabi was just pure power. I would say if you have to say force of the 3, I would go with Mugabi. His punches on Hargrove were frightening. They could have knocked out a heavyweight.
Julian Jackson. It looks as if he doesn't even put that much into a punch, yet it would probably end up a nasty ko. Frightening power. He layed people out like tablecloths.
MIGHT crack the top 50 BUT a relatively similar styled puncher was lew jenkins who should be in the conversation. that one's for you bb :good