Improving the .40S&W

This page was written when I heard a rumor that the US Army intended to replace its 9mm pistols, and the idea was offered that the .40S&W would be the round of choice rather than the logical choice of the .45ACP. I intend to review why the .40S&W has become so popular, how it can be made more effective and why it cannot replace the .45 but may have a place as a supplement.

A combat or self defence pistol has the rapid incapacitation of the target as its main requirement. A hit target should rapidly cease any aggressive activity. For military use the best choice is obviously a pistol chambered in .45ACP. Many of the criticisms made about .45 pistols are groundless or only applicable to the M1911A1.

The claim that the .45 has a fierce recoil is quite false. Recoil energy and Recoil velocity gives us an indication of the force a particular weapon/round combination will exert. While recoil energy determines how hard the blow to the shooter feels, recoil velocity determines how fast the gun comes back at the shooter. The faster a gun comes back at you the less comfortable. This is because your body has less time to give with the recoil.

Recoil of a .45 M1911A1 firing a 230gr at 832 fps is 5 ftlbs at 11 feet per second, while that of a 9mm Glock 19 firing a 115gr at 1,167 fps is 5 ftlbs at 15 feet per second. With a 124gr bullet at 1,249 fps, which approximates the NATO standard load, the Glock 19 produces 7 ftlbs at 18 fps. A .45 Glock 21 with the 230gr round gives 7 ftlbs at 17 fps. So a .45 M1911A1 has less recoil than an 9mm Glock 19 and a 45 Glock 21 about the same as 9mm Glock 19.

Many modern .45s are now available with recoil-reducing compensator systems. Polymer frames are also said to reduce the perceived recoil.

Another claim is that the .45 is heavy, and that this is uncomfortable if carried for prolonged periods. The long-barrelled M1911A1 is a heavy weapon. Many modern .45s are made of lighter materials such as alloys and polymers and are often available as compact, concealable models.

Objections that the .45 has a low magazine capacity are also no longer valid. Many modern .45s have high capacity magazines, with weapons such as the Glock 45s holding 13 rounds. Many of these also offer double action triggers.

A more valid criticism of modern 45s is that double column magazines make the grips too wide for shooters with small hands. Some manufacturers also offer weapons with single column magazines, but obviously these have a lower magazine capacity. Thinner grip panels and redesigned frames will go some way to addressing this problem.

In recent years the .40 S&W has gained popularity in police and civilian circles. The ancestry of this round dates back to the 70s and a wildcat cartridge called the .40 G&A. Intention was to try and produce a round with the stopping power of a .45 in a weapon with the size and capacity of a 9mm. It wasn't then appreciated then that the diameter and weight of the .45 was more of a factor for the round's effectiveness than its energy. It's also apparent that the creators were trying to emulate the then popular 185gr .45 JHP. Improvements in hollow-point design have now given us a more effective and reliable 230gr JHP.

The .40 G&A was developed into the more powerful 10mm Auto for use in the Bren Ten pistol. This longer round needed a weapon with a .45 sized frame. Following the Miami shootout the FBI became very interested in high penetration rounds and the 10mm cartridge. However, when they adopted it they found that it was too powerful for some of their agents to handle, so they produced a medium velocity version, sometimes called the 10mm Lite. Smith and Wesson realized that they could get the same performance as the 10mm Lite with a shorter case, and that this round could be adapted to frames and magazines of weapons originally intended for the 9x19mm. This round was to become the .40 S&W.

The .40 S&W seemed an attractive proposition to Law Enforcement Officers. It could be used in a 9mm sized automatic and offered an increase in power while maintaining a high magazine capacity. The original .40 S&W produced ballistics similar to the .38-40 revolver round, offering a 180gr bullet at 950-980 fps. Comparisons with the 10mm and .45 caused some to call it the “.40 Short & Weak”.

Soon the .40 S&W was being offered in high velocity 135-150gr loadings at 1,250-1,350 fps. The intention was obviously to produce a round of similar performance to the 125gr .357 magnum, which due to the flawed design of the Marshall and Sanow study was being widely reported as a nearly perfect (96%) manstopper. In fact this study failed to take into account bullet placement, so was biased towards loads that were popular with well practiced combat shooters such as police officers.

As we will see later, both the .40 S&W and .357 magnum are actually a lot less effective than the .45ACP. This is not well known, however, and in other respects the .40 S&W looks attractive.

Several years ago there was an extensive and well-designed investigation into the incapacitation capabilities of various rounds. This survey was paid for by a group of body armour manufactures who chose not to widely circulate the results. This at least saved the blushes of many gunwriters and manufacturers, but has denied a lot of people information that might save their lives.

One finding of the tests was that the .45ACP was a much more effective round than the 9x19mm. Many people have held this opinion for decades, but now here was concrete scientific proof. The .44spl, .44mag and .45 Colt also proved to be more effective.

A surprise to many was that high-velocity medium rounds such as the .357, .40 S&W and 10mm Auto also proved to be much less effective than any of the large-calibre rounds. The reasons for this are explained in greater detail here.

Yet another surprise was that one medium-calibre round did have a similar performance to the big bores, and that it was a 200gr .38. With both LRN and soft point ammo the 200gr .38 beat any other medium-calibre and was comparable to the large bores. Tests indicated that pistol bullets lighter than 200gr were far more likely to be deflected by an impact and veer off path, missing the internal structures that they were aimed at.

The actual papers on these tests are not widely available, but we do have some collaborating evidence. In 1904 the US Ordinance Board tested a broad range of the automatic and revolver ammunition then available. They found that within the velocity ranges possible with handguns there is no marked effect from increased velocity alone other than greater penetration. The weight of the bullet seemed to be important, since it was noted that the most effective bullets were not only of large calibre, but also the heaviest weight. The diameter or calibreof the bullet was important because at handgun velocities expansion of soft point or other expanding bullets is not reliable. The larger diameter bullets simply destroy more tissue and blood vessels because they affect a larger cross-sectional area and attack it with more weight. Their recommendations lead to the adoption of the 230gr .45 ACP.

In the 1920s there was a similar set of experiments conducted in Britain. The conclusion of this trial was that diameter of the projectile made less difference than weight. Weight and velocity were the most important factors and the velocity had to be low, not high. They concluded that a 200gr projectile travelling at an initial velocity of about 650 fps was ideal for good short-range stopping power. The reason for the low velocity was so that the bullet would expend its entire energy within the target and not carry on through.

The British trials were followed by the adoption of the .38/200 cartridge, which was the commercially available .38 S&W known as the “Super Police” when loaded with a 200gr bullet. It was known officially as the “.380 Revolver Mk I” and had a 200gr. bullet of .359" diameter that developed a muzzle velocity of 600-650 fps. It was to replace their .455 Webley which had a 265gr bullet with a MV of 600 fps.

It is possible that the importance of calibre may have been played down in the British trials, since the objective had been to adopt a smaller weapon than the .455. It is, however, notable that .38 S&W in its more common 150gr load was not found sufficient. Whether the .38/200 was truly the equal of the .455 has never been settled, but many sources agree that the .38/200 was still an effective manstopper. Interesting is that this is the only positive comments about the stopping power of a medium-calibre non-magnum velocity round that I have even come across. Following German accusations of Hague Convention violation (which didn’t actually apply!) the lead round of the .38 was replaced by a 178gr jacketed one.

It can be challenged that we have pistol rounds capable of higher velocities than in 1904 or the 1920s. The 1904 trial did include the 7.62mm Luger at 1,420 fps. Fastest pistol-type round I can think of is the .30 round fired at 1,990 fps from the M1 carbine. Numerous combat reports confirm that this is inferior to the .45ACP in stopping power. The 1904 conclusion about handgun velocity seems to be still correct.

Another objection is that although that 1904 trial included lead and soft-point rounds, it didn't include modern hollow-points. Does the combination of modern high velocities and hollow-point ammo change things? The trails in the 1990s did test these rounds. Although we now have jacketed hollow-points that will expand with much less energy than those in use in the 60s, expansion is still not certain from handguns.

What makes a hollow-point mushroom is the energy the bullet has at the moment of impact. The energy of a bullet is given by the formulae “Energy = ½ x Mass x Velocity²”

A small reduction in weight that gives a small increase velocity will give a big increase in energy. This all looks very sexy on the pages of a magazine article, but works both ways. For every inch of air that a round travels through it sheds a bit of velocity, and a small decrease in velocity means a big decrease in energy. Weight, on the other hand, remains constant. A heavy bullet will usually arrive with more of its initial energy than a lighter one, unless the range is very short. Light, high-velocity loads are best reserved for applications such as home defence when range will never exceed more than a couple of metres.

Even when they do expand, many medium-calibre rounds produce a wound channel not much wider than that of an unexpanded .45 , and this was confirmed by the experiments in the 90s.

On another page I’ve pointed out that the application of the above findings would make .38/.357 J-frame revolvers very effective defensive weapons if used with a heavier load. A revolver can handle bullets of a shape or malleability that would not feed through an automatic.

What was also evident from these tests is that many of the rounds and weapons being touted in advertisments and the media as being good self-defence weapons are at best mediocre.

Currently the heaviest bullet offered in preloaded .40 S&W ammo is 180gr, which the tests described above found to be too light for good terminal effects.

Handloaders have fitted bullets of up to 220gr into the .40 S&W case. FMJ, TMJ and JHP bullets of 200gr are available and can be propelled at a muzzle velocity of around 950 fps. While this only gives a modest sounding 400 ftlbs of muzzle energy, the important consideration is not how much energy a bullet has at the muzzle but how much it has at the target and how it utilizes it. The 200gr will have retained more of its initial energy and will use it more effectively for penetration and mushrooming. Slow, heavy bullets have proven to be more consistent manstoppers than faster, lighter rounds with much greater energy.

Hollow point 200gr loads for the .40 should be loaded at 950 fps, while military FMJ loads at a lower velocity such as 850-875 fps. Since we are considering the .40S&W for military applications, we need to consider how this load will perform with FMJ/TMJ bullets. Using Veral Smith’s formulae for non-expanding pistol rounds we can predict that a 200gr TMJ at 950 fps with a 0.3" Meplat will only penetrate 18"of flesh. Rounds of around 857 fps will produce around 16". Hollow point 200gr rounds that expand will probably give 12-15" of penetration, which is close to ideal.

With a 200gr bullet the .40 becomes the .40/200 or .40 Slow & Weighty, and is likely to be far more effective than the currently offered high-velocity loads. Calculations also predict that it will produce less recoil than the lighter faster rounds.

The TKO figure of 10.02 for the 135gr .40 suggest that it is likely to be slightly more effective than 125gr 357’s TKO of 9.24, although this does not allow for bullet design or configuration. The revolver round can potentially carry bullets of a shape or softness that would not feed through an automatic. One interesting point is that the 135gr .40 has a relatively low sectional density for a pistol round (0.12), and the effect of this can be seen at longer ranges, where it has only 85% of its original velocity at 50yards, compared to 90-97% for bullets of more usual sectional density. At 25yds+ the 135gr has lower momentum and TKO values than the 125gr 357.

The 200gr .40 gives a SD of 0.18, and TKOs of 9.79 at 857 fps, 10.00 at 875 fps and 10.86 at 950 fps. I don’t have any figures for velocity of 200gr at 50yds, but given the sectional density would expect loss to be no more than 3%. This long range capability makes the round more suitable for military use.

The .40 S&W will never as effective as a .45ACP, especially if the user is restricted to FMJ ammunition. The .45 will always be first choice if deliberately going into a combat situation. I see the .40 as a supplementary weapon rather than a replacement. It may be a more convenient weapon to carry in plain-clothes applications or in a medium-threat application. It may also be more suited to individuals with small hands who cannot handle the broader grip of a double-stack .45.

The wider availability of 200gr ammo will greatly increase the .40 S&W’s potential as an effective combat weapon.

While calculating the recoil figures above, out of curiosity I decided to make some others. The sample rounds I used were:

The 124gr 9mm and 230gr .45ACP are very similar to the military rounds commonly used in these chamberings.

No real surprise that the smaller rounds produce less recoil when fired from weapons of the same weight. If choosing a smaller-calibre it is usually so one can use a lighter weapon. SIG-Sauer offer pistols in several calibres, and most chamberings have a model of around 28oz.

I also calculated figures for some pistols in the Glock range, since these represent some of the lightest examples of weapons commonly used.

Winfried Hundt wrote to me pointing out that recoil is produced by the recoil impulse. Here are some calculations for the above loadings including recoil impulse values too. I used the Handloads.com Recoil Calculator for this which gave slightly different values for energy and velocity.

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