All things being equal (size, weight, technique), muscle type has plenty to do with power. When ol' timers say he's "born" with it, thats what they're talking about. Some people are born with as high as 80%fast twitch. These guys are more capable of explosive movements. These guys throws fast snappy punches. Compound this with proper technique and leverage starting from the legs to the punch than you got someone who can throw those he-didn't-see-it-coming kinda punches which only doubles its effectiveness.
Muscle mass plays the biggest part in tandem with technique. One guy might weigh 200 pounds but only 40 pounds are used when he is punching the other guy might be 130 pounds but uses of of his body to generate power. The best body type would be tall , thin shoulders and long arms. Their body mass does not need to swivel to far through their shoulders and their long arms can build up speed and momentem to partner up with all of the mass that is going through with their shots. Muscle bound guys have built up their muscles for looks and not to do anything really, you could strip half of their muscles (the right ones) and they still would generate the same power.
the better question is how much muscle is needed to achieve the hardest punch. i remembered roach saying that khan has too much muscle and he has to lose some.
No, a tall thin guy with snap can hurt you more than a short musclebound guy who doesn't have leverage. I'm going to up the ante here and even say sometimes muscles don't even help IN LIFTING WEIGHTS. They are some super strong guys that are very lightly muscled with high neuromuscular efficiency, way way stronger than they look.
:rofl Your joking, right? Holyfield.never hit as hard as Foreman! A prime Holyfield had to drop Moorer 5 times before stopping him while a faded 45 yr old Foreman it only took one shot to put Moorer down!
It has been said, that maximum power is a compromise between max strength (slow but capable of shifting heaviest load) and max speed, favouring speed at about 2/3 ratio. Using that logic, the highest jumps are done at about 2/3 of maximum speed. Muscle mass doesn't equal strength and can hinder speed, so in the end it's all about efficiency.
Really hard punchers are born, not made. This is a fact. Andre Ward is a prime example. He is freakishly strong, can physically manhandle big guys like Froch and Green, yet he hits like a girl. He hits these guys a 100 times square in the face literally, and does not even come close to knocking them out. All that weightlifting does make you a massive puncher.