Kinetic energy (foot pounds) is really not a good predictor of bullet effectiveness. A single neutron at warp 9 and a 325 grain 45 caliber bullet might have the same KE, but produce very different results.
Momentum is a bit better predictor. Momentum is conserved when a bullet impacts.
Kinetic energy is the better predictor here:
Hornady 40 Smith & Wesson 175 gr FlexLock @ 1010 fps:
396 ft lbs
Hornady 223 Remington 55 gr TAP URBAN @ 2983 fps:
1087 ft lbs
Hornady 40 Smith & Wesson 175 gr FlexLock @ 1010 fps:
25.3 lb-ft/s
Hornady 223 Remington 55 gr TAP URBAN @ 2983 fps:
23.4 lb-ft/s
