I figure you're comparing factory ammo. There are web sites for each ammo manufacturer that will give you ballistic specifications for their ammo. Check out Winchester, Federal, CCI, etc.
Normally you'll find on the ammo box the weight of the bullet expressed in grains, velocity at muzzle in feet per second, and energy at muzzle in foot pounds. There is an equation to calculate this energy if your pistol produces a different velocity as the manufacturer nomally tests their ammunition in a barrel of a specific length. Manufacturer's specs will tell you this. Example: 9mm is normally tested in a 4" barrel.
You will note that bullets with the same weight but traveling at different velocities will have different energies.
Here's the equation: bullet grains x velocity squared /450400 = 115 gr x 1280 fps x 1280 fps / 450400 = 418 ft lb.
Manufacturers will produce different types of ammo by using different powders and different amounts of powders. To further the confusion you'll find ammo that's marked +P and +P+. These cartridges will exceed normal cartridge pressures. Please ensure that your pistol can handle these cartridges or you'll end up with a KaBoom.
For premium ammo checkout at Cor-Bon ammunition at
www.corbon.com
Their self defense ammo for 9mm+P 115 gr JHP develops 1350 fps and 465 ft lbs.
Hope this helps.
