alright here comes the answer you should pay attention to:
im not a professional boxer, but i have dabbled and i do work at a boxing gym with ring and all kinds of bags, etc.
i can pound the speed bag as good as anyone in that gym, including roger leonard- sugars brother, who trains people at my gym three days a week.
heres the deal- i have never wrapped my hands. i also dont get red knuckles-pinky or any other, because you arent supposed to hit it with your knuckles. people are responding with all this oh no thats going to screw up the way you hit blah blah. the speed bag is designed to get you to move you hands fast, not work on your punching technique.
when you actually punch someone you are bringing your hand back to your body and putting all of your body and power behind it as you push relatively straight out- obviously different for hooks and uppers and such but the point is there isnt a legal boxing punch that follows the form of the speed bag. you should be connecting with the bag with the lower corner of your palm, the meaty part *if youre looking at your hand palm facing up i consider the lower outside corner to be the part straight down from your pinky–so yes, almost your wrist joint.
some people also have tougher hands than others- my little brother is 13 and i take him to the gym with me a couple days a week, started him off hitting the speed bag one hand at a time, the alternating hands two hits right, two hits left, two hits right, etc.
right now were working on alternating the hands doing singles- hes very good, and the fact that hes 13 i think hes way ahead of his friends and such- anyway, his hands were always red so i just bought him some wraps- sometimes my hands get a little red, but not like his—so wraps i think are a preference thing, however i have never let him hit the speed bag with his knuckles- that is not a preference thing as far as i am concerned