In the world of high school geometry (you knew that was going to come back to bite you one day- and it just did..) there is a big difference between “diameter” and “area” where the diameter is a 1 mm difference the area of the circle is 1.12 inches for a 9mm and 1.26 inches for a 10mm or a 12% increase for the 10mm.
Think back to H.S. Physics....
Kinetic Energy = 1/2 X Mass X (Velocity)Squared
KE=1/2MV^2
Yes, Kinetic Energy isn't the end all and only measurement of the damage a round can do, just as important is how much energy you can impart on the target to do damage.
But Kinetic Energy is a big factor to consider, and often the biggest truth teller of how much damage it can do.
And KE is why the tiny 9mm can even compete with the big ol' .45 ACP, they are roughly the same KE, some of the hotter NATO and +P's are more than .45 ACP. Most range ammo on the market the MV varies (and that is a huge factor in the KE) and its a toss up, some 9mm has more KE than .45ACP and some .45ACP has more KE than 9mm.
That is truth teller on the 10mm, roughly 50% more KE than the closely even 9mm and .45 ACP.
BUT, only roughly a 10% increase in felt recoil over .45 ACP.
Granted, 10MM is a 50% increase in felt recoil over 9mm. I'm using Power Factor for the ammo to compare the felt recoil.
Most 9mm and .45ACP is a little more or less than 400 ft-lbs of KE.
Most 10mm is a little more or less than 600 ft-lbs of KE.
And yes, all three calipers have lots of commonly available ammo that is almost 100 ft-lbs less than those figures, as well as less commonly available ammo that is also almost 100 ft-lbs more than those figures. So yes there are lots of games that can be played saying look at this compared to this, its not that much more or less.....