Unlike the tried and true 9mm, the .40 Smith & Wesson is one of the newest major handgun calibers, dating back only 25 years. It’s a spinoff of the 10mm Auto, using a reduced load in a shorter case. The aim was to allow existing 9mm designs to be modified for the larger round without needing expensive reworking of the frame, while still matching the performance of the FBI’s medium-power 10mm load. The modifications were simple; bullet diameter and case head design stayed almost unchanged, while the case was shortened from 25.2mm to 21.59mm. Along with a more deeply seated bullet that gave an overall length identical to the 9mm at around 29mm. Both the 9mm and the 40 cal make decent guns for beginners and usually the handguns are similar in size making them both easy to store in your car or in a smaller safe in your home office. With the lengths of the bullets and each gun being so close in size, it makes the two rounds natural competitors, so let’s look at how they stack up as survival calibers. The S&W 40 Cal for Survival: Although S&W developed the cartridge in cooperation with Winchester, and were the first to start work on a weapon to fire it, they were beaten to market by Glock. The Austrian company released .40 versions of their popular Model 17 and 19 weapons a week before the S&W Model 4006 went on sale. Since then several other manufacturers have produced .40 weapons including SIG Sauer, Beretta and Springfield. It’s been well received by many US law enforcement agencies. The FBI, concluding that 10mm was more trouble than it was worth, switched to .40 in the Glock 23. The US Coast Guard chose the .40 version of SIG’s P229R-DAK. Many local police departments also switched to it, some replacing .38 revolvers and others moving up from existing 9mm semi autos. It’s a effective round. Like the 9mm it’s a high-pressure loading; both are rated up to 35,000 psi compared to 21,000 for .45 ACP. Most 9mm loads have a higher muzzle velocity but to compensate for that the .40 throws a much heavier bullet – typical loads run from 155 to 180 grain, compared to between 115 and 147 grain for the German round. That translates into higher muzzle energy; while +P loads in both rounds are similar, at around 500 ft lb, a typical 9mm puts out closer to 430. The average .40 round delivers around 475 ft lb, an improvement of about 10%. Either of them is an effective survival cartridge but the .40 has an edge. How does it hold up versus the 9MM? One reason for the popularity of 9mm handguns is their magazine capacity. Few full-size nines these days hold less than fifteen rounds and several can fit 17 in a standard magazine. Shooters have come to like having this firepower to hand and many would be reluctant to see capacity reduced. Obviously, with the .40 having a larger diameter, it’s not physically possible to stuff as many into the same space, but modern designs are doing pretty well. The SIG P226 has a thirteen-round capacity as standard while the Glock 22 holds fifteen. Expect to lose two rounds from a standard magazine in exchange for that extra power – it’s not a bad tradeoff at all. When it comes to handling and usability there isn’t a lot to choose between the two. Because the .40 was designed to fit in 9mm-derived weapons there isn’t any ergonomic penalty, whereas many 10mm designs have bulkier grips that don’t suit small hands. As for recoil, that’s a question of physics; more energy out the muzzle means more recoil. While it’s slightly heavier it isn’t a dramatic difference, and unless a 9mm is at the limit of what you can handle it’s not likely you’ll have trouble with a .40. There is one potential concern that might persuade you to stay with 9mm. Unfortunately .40 designs, especially older Glocks, are prone to case failures. The size and geometry of the case means a relatively large feed ramp, and often an unsupported area at the lower rear of the case. Occasionally that leads to a burst case and, usually, a wrecked pistol. It’s not a common event but it is more likely to happen with a .40 than a 9mm. I If your life depends on your handgun the last thing you want is for it to unexpectedly destroy itself when you pull the trigger. If you do opt for a .40 that doesn’t support the case avoid using reloaded ammunition and consider using post-1996 Federal ammo, which has a strengthened case. Also rotate the ammunition in your carry magazines. If a round is repeatedly chambered and ejected the bullet can slowly be pushed back into the case; even a fraction of an inch is enough to raise pressure and increase the chance of a burst case, so when you go to the range fire off your loaded magazines first then reload them with fresh ammo. Wrap Up: Overall the .40 makes a good choice for a survival gun and as we said earlier is a choice for beginners. It’s just as effective on target than the 9mm without giving away much in the way of magazine capacity and we’d always make sure to have at least one of them locked up for emergencies. In a prolonged survival situation we’d still choose the 9mm because 9mm ammo is ubiquitous and the 40 won’t be as easy to keep it fed, , but apart from that it’s a powerful, easily handled caliber that won’t let you down when you need it most.