Originally Posted By: Pete591
Originally Posted By: chevrofreak
Ah the myth of the all mighty .45ACP
It all boils down to this equation when it comes to caliber stopping power and shear force which is all about penetration and HP expansion.
Kinetic Energy (Brutal Impact Force) = 1/2 MV squared
KE is expressed in Joules and one Joule is what it takes to launch a tennis ball to the speed of 20 mph. So one Joule is a lot!
- A Buffalo Bore
+P .45 ACP has a KE of
165 million Joules of Energy and this is the max. for this caliber for all practical purposes under SAMI loading specs.
- FBI says that "fast and light"
155 gr .40 S&W rounds traveling 1,150 ft/sec are most effective in this caliber and also at the SAMI max for this caliber. That's
102 MIllion Joules of Energy.
-9 mm 124 +P+ at 1,250 ft/sec will give
97 Million Joules of Energy and this would be a SAMI max with the +P+ as well for this caliber.
In summary:
- .45 ACP 230 gr +P = 165 Million Joules
-.40 S&W 155 gr = 102 MIllion Joules
-9 mm 124 gr +P+ = 97 MIllion Joules
So Winchester Lawman 124 gr +P+ is just as capable (powerful as in KE and field performance with this round) as the .40 S&W 155 gr rounds used by LE and available commercially as well. It even expands to about the same wound channel too. Glocks etc will not maybe like a "steady diet" of +P+ but they are designed to take it. I have used this myself and it is not much hotter in feel than a +p.
The .45 ACP is a big jump from both the SAMI max's and KE of the 9mm and the .40 S&W. (Also now called the "short and wimpy" by some LE guys these days. The .45 ACP has 60% more energy and that means it has the potential to penetrate better (FBI says lack of penetration is what gets you killed the fastest)/expand better (so you get max penetration and wound channel without shooting through) and all this finally translates into stopping
a perp. on drugs who dosen't feel pain and is not in shock of being shot.
Just the facts! It's why the military just ordered thousands of 1911's to replace Beretta's and .40 Sigs and so did the FBI Elite Forces. It's a learning curve through everyday experience I would imagine.
Just my .02
Your equation for Kinetic Energy (KE) is correct (i.e., KE = 1/2 M*V^2), however your numbers for the kinetic energy of various rounds are all wrong. NO handgun fires a projectile with a muzzle energy in the MJ (Mega Joule, i.e millions of Joules) range. If you fired a handgun with a muzzle energy of a hundred Mega Joules (MJ), the gun would be vaporized, the recoil would blast you backwards a mile or two and you'd either be vaporized yourself in the process or reduced to a pile of bloody goo.
A .45 ACP will generally have a muzzle energy around 440 Joules (give or take). A 9mm will have a muzzle energy around 460 Joules (also give or take). That said, kinetic energy isn't the last word, there are several different other variables in play. For one, the muzzle energy isn't as important as how much energy is delivered into the target. For instance, if you shoot someone with a 9mm Luger with a FMJ round there is a decent chance that the lighter/faster FMJ bullet will over penetrate and go out the backside of the bad guy. In this case you might only deliver 60% of the available kinetic energy into the target. The other thing to consider is how the delivered kinetic energy translates into tissue damage.
In general, the larger slower rounds like the .45 ACP do seem to have a *slight* advantage in translating delivered kinetic energy into wound trauma (when talking about rounds with roughly similar kinetic energy at the target), though the difference is less that most .45 ACP aficionados would like to admit. Early on, the 9mm got something of a bad reputation in this country since in the early days most people were shooting either FMJ or JHP rounds that were not specifically designed for the 9mm's projectile weight and velocity (and consequently expanded very poorly or just fragmented into many little pieces). Now that excellent 9mm JHP is readily available these early problems have been by and large resolved.
Given correct ammo for a 9mm Luger, I think that they can perform in the same league as the .45 ACP and they do have some advantages in ease of carry/concealment and recoil, while on the other hand I would give the edge to the .45 ACP in terms of sheer "intimidation factor". I personally would not feel under armed with either class of weapon and I sure as heck wouldn't want to be on the receiving end of either gun.
BTW, for future reference it is most common in the U.S. to see muzzle energy given in ft*lbs (foot pounds). The conversion factor for ft*lbs to Joules is 1:1.356, i.e. 1 ft*lb equals 1.356 Joules.
-Scott