The .45 Automatic
Max Pressure 19,900cup/22000psi (standard)
                       23,000cup               (+P) *
                       28,000+cup ?           (.45 Super)**
                        38,000 cup               (.460 Rowlan)***
    This is considered by myself and many gun experts to be the ideal defensive handgun cartridge. Even those who tout other cartridges do not deny the power and reliability of the classic .45 A.C.P. The perceived flaws and weaknesses of this fine cartridge, are a matter of dispute, and in any event, have recently been remedied. The dispute centers around what the purpose of a hand gun should be, and how powerful it needs to be in order to fulfill this purpose. The generally accepted purpose of a handgun is for defense. It needs to be small and light enough to be carried comfortably at all times, concealed if necessary, and it needs to be quick to bring into action. It also needs to be powerful enough to stop an attacker as quickly as possible. We tend to have an attitude, these days, that more, bigger, faster is better, but in some cases this is not true.
    The most powerful handgun in the world, is likely the Thompson Contender with a barrel chambered in one of the many rifle calibers available for it. This would make a poor defense gun, though it is an excellent hunting tool. The hunter stalks his prey, and chooses the time and place of the encounter, ideally killing with one shot. In a defensive situation, YOU are the prey, and where the aggressor has had time to plan out his actions, you must react quickly, and decisively. This requires a gun of a certain size and weight. This combination of requirements, the need to hit fast, and the need to hit hard, requires some trade offs. A .44 magnum hits very hard indeed, but the recoil is so intense that you had better hit your target with the first shot; by the time you are ready for a second shot you may be hit several times by an opponents less powerful, but faster firing gun. On the other hand you can pop off .22 rounds and keep the gun on target as long as you like, but the .22 is not exactly known as a fight stopper. The .45 fires a large heavy projectile, and it fires it at a high enough velocity to penetrate and do lethal damage. At the same time, it is not so powerful that a reasonably well trained person can not control it in rapid fire. The gun is tried and true, and the section on bullet lethality will go into more detail about the trade offs made and the results achieved.
      The few perceived shortcomings of the .45 Auto round have been addressed in the last decade or so. One of them is the chamber pressure limit which keeps the 230 grain bullet in the 800 to 900 fps range. I do not particularly consider this to be a handicap, but for those who do, there is the fully supported chamber, and the .45 Super round, along with some others. The fully supported chamber eliminates the major weakness of the original design which left a small section of brass exposed near the base of the cartridge, If pressure limits were exceeded, the case could burst. This is not quite so threatening as a blown cylinder in a revolver, but a burst case, venting hot gasses down into a magazine full of live cartridges, is no joke, particularly when the shooters' hand is wrapped around them. There is also some new brass out there. You can buy .45 +P brass now, which I imagine is stronger than standard .45 brass. There is also the new .45 Super brass, and ammunition.
      The other perceived handicap of the gun was not really a consideration until the seventies, or possibly the late sixties. The new generation of "Wonder Nines" were nine millimeter autos with double column magazines which could hold twice as many rounds as the .45's seven. This was not a factor earlier because prior to the early seventies there was only one pistol which was so designed, and that was the Browning P-35, also known as the Hi-Power. The gun was expensive, and most shooters thought it better to have 7+1 rounds of a proven, and effective manstopper than the Brownings' 13+1 in a less effective cartridge.
    In the fifties, the government announced a competition for a new 9mm service pistol to replace the aging stock of "old ugly" M1911 .45 autos.  It was also announced that the new pistol should be somewhat lighter than the old model it was replacing. Colt's response was to rechamber the classic M1911 for 9mm, and to shorten the gun a bit. Smith and Wesson responded by introducing the M-39. The M-39 was a double action 9mm, with an alloy frame.  The government changed it's mind, keeping the old Colt .45 auto for another three decades, and the contract was never filled. The M-39 was offered to civilians and to police departments, and developed a certain following. The double action trigger had previously only been available on much more expensive guns, as had the use of an alloy frame. In 1973, the gun was modified by widening the magazine well for use of a double column mag, and was introduced as the M-59, the first of a long line of affordable double column "Wonder Nines" which they are still producing. Other manufacturers followed suit, and soon you did not have to be rich to own a double column gun.
    There were also some tests conducted, at about this same time, which on paper "proved" that the 9mm, in its' lighter, higher velocity loadings was a better cartridge than the "old, slow" .45. These tests have since been discredited, and are covered in more detail in the bullet lethality section. Even for those who still cling to these discredited tests, there is the fact that, as mentioned above, the .45 can now exceed the velocity of the 9mm with new brass and supported chamber guns. The so called magazine capacity deficiency has also been taken care of by Glock, Para Ordinance, H&K, and some other companies which now make .45 pistols with double column magazines which hold from 12 to 15 rounds. I have two carbines, the Mech-Tech, and the Marlin Camp Gun which fire this round. I also have several pistols, the Glock 21, Para Ordinance P-12, Para Ordinance P-14, the S&W M-1917, H&K USP, and the Colt Gold Cup. If you can not help yourself, you can find out about the .45 Super from a real expert: Ace Hindeman. He produces guns, spring kits, modification kits, and has worked up safe loads for the caliber. He is in my list of gun links.

*the higher pressures shown are for suitable firearms with fully supported chambers only
**The only gun which is listed by the manufacturer to fire .45 Super rounds without spring and/or barrel mods is the H&K USP
***Specially modified guns only.

Cartridge dimensions