I'm not sure what video you were watching but caliber does matter for action pistol type competition (IDPA/USPSA). Both require a pistol shooting 9mm/38 Spcl or bigger with a certain "power factor" (bullet weight x velocity /1000: 180 grain bullet at 100ft/s /1000 =180 PF), minimum being around 125. IDPA breaks out classifications by pistol type and scoring is the same for everything in that class. USPSA has "Minor" and "Major" for each class (except Production that is only Minor for every gun) based on power factor. 125-164 Minor, 165+ Major and the targets are scored diferently based on where you hit it. CoM is scored the same for both but hits outside of that are scored lower (higher penality) for Minor. It is a trade off of speed vs accuracy. If you can always hit the center faster with the smaller bullet, better scores. If you don't hit center everytime, heavier bullet better score. 40 and 45 factory ammo is almost always major and 9mm/ 38 Spcl is almost always minor.