380 ACP vs 9mm

Banana Ballistics • July 13, 2023

So, you want a new carry gun but just can’t decide between the 380 and the 9mm? Considering that these are two of the most popular carry choices currently available, it is easy to see why it is such a difficult decision. Luckily, this article will be going over the benefits of each cartridge to help make your decision a little easier.

Physical attributes

Stood side by side, it is easy to see that the 9mm stands much taller than the 380. With an empty case length of 0.754 inches, the 9mm case stands over 1/16 of an inch taller than the 380, which has an empty case length of 0.680 inches.

This extra length gives the 9mm a capacity of approximately* 13.30 grains of H2O compared to the 380’s capacity of approximately* 11.8 grains of H2O. An increase of 1.5 grains of H2O may not seem like all that much, but this small difference gives the 9mm a 12.7 percent increase in H2O capacity over the 380.

If you noticed that the 380 and the 9mm appear to be using the same diameter projectile, you would be correct. Although the naming can be confusing, both the 9mm and the 380 utilize 0.355” diameter projectiles (0.356” diameter projectiles are common for cast/plated bullets). Do NOT, however, be confused into thinking that they use the same projectiles though.

9mm-specific bullets typically weigh between 115 to 150 grains and are much too long/heavy to be seated into a 380 case. 380-specific bullets on the other hand, typically weigh between 85 to 100 grains and are generally too short for most 9mm handguns to feed them reliably. Because of this, reloaders should be careful when choosing projectiles for either cartridge.

It should be noted that lighter bullets do exist for each cartridge, though they are typically made of a solid copper or similar alloy.

Power

Based on the size difference between these cases, it would be easy to assume that the 9mm produces more kinetic energy than the 380. Although this assumption is correct, the reasoning for this difference in kinetic energy is not solely based on the difference in size. Perhaps the biggest difference between the 9mm and the 380, is the pressure at which each cartridge is operating.

According to SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute), a standard 9mm has a maximum pressure rating of 35,000 psi. This is much higher than a standard 380’s maximum pressure rating of 21,500 psi. Having an extra 13,500 psi, or approximately 62.8 percent over the 380, helps the 9mm produce considerably more kinetic energy than the 380.

In fact, Winchester’s 115 gr FMJ offering in 9mm produces 362 ft/lbs. of energy at a muzzle velocity of 1190 feet per second. Winchester’s 95 gr FMJ offering in 380 only produces 190 ft/lbs. at a muzzle velocity of 955 feet per second, or about half the muzzle energy of the 9mm. This is not to say that the 380 is inadequate for self-defense. However, its penetration capabilities may not compete with 9mm on certain materials.

If your handgun is rated for +P (added pressure) ammunition, however, the 380 gains considerably more performance than standard pressure offerings. If we look at Underwood’s 90 gr XTP +P offering in 380, we see that it produces 288 ft/lbs. of kinetic energy at a muzzle velocity of 1200 feet per second. This is nearly 100 ft/lbs. more than a standard 380 load, which places it close to standard 9mm territory.

We do have to keep in mind, however, that the 9mm also has +P offerings**, which changes its performance considerably as well. If we look at Underwood’s 115 gr hollow point offering in 9mm, we see that it produces 432 ft/lbs. of kinetic energy at a muzzle velocity of 1300 feet per second. While this may not be quite the jump in performance that the 380 experienced, this load is still producing nearly 150 ft/lbs. more kinetic energy than the 380 at the muzzle.

** +P ammunition is not safe to fire out of every handgun. Always verify that your handgun is rated for +P ammunition before purchasing this ammo designation.

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Recoil

Given that the 9mm produces more kinetic energy than the 380, it would be easy to think that it also produces more recoil. While this might be true if both cartridges were fired from the same size handgun, finding the same size handgun can be a bit of a chore. Although it is possible to find identical size handguns chambered in either cartridge (such as the Sig P365), this is not typically the case.

To maximize concealability, 380-chambered handguns are typically designed around ultra-compact profiles, many of which do not even weigh a full pound. The 9mm on the other hand, with its larger size and extra pressure, is not able to use these ultra-compact frames. With the larger size requirements, 9mm handguns typically weigh more than 380 counterparts.  

If we look at the Ruger MAX series of handguns for example, we find that the MAX-LCP in 380 weighs 10.6 ounces (unloaded). The MAX-9 by comparison, weighs 18.4 ounces (unloaded), or approximately 1.75 times more than the MAX-LCP. This extra weight may be a drawback on your belt, but it does provide one major benefit.

As weight increases, felt recoil begins to decrease. Because of the lightweight nature of 380-chambered handguns, recoil is often described as being much snappier than most 9mms. Without proper training/practice, this increased recoil makes it more difficult to stay on target, which is not ideal in self-defense situations.

If you are new to handguns or have weak wrists, you might want to avoid ultra-compact handguns like the Ruger LCP as a first purchase. 9mm handguns may not be quite as concealable, but recent advancements in design have proven to maximize capacity while only being marginally larger than 380 counterparts.

Cost

Well, if the 380 doesn’t compete in terms of ballistics and usually has more recoil, surely it doesn’t cost as much as 9mm, right? Unfortunately, this is not the case as many 380 offerings mirror or even surpass 9mm prices. The biggest difference in price is usually found in range/target load offerings, where the 380 can cost as much as 40 percent more than the 9mm in the same ammo line.

The 380 may not use quite as much material as the 9mm to produce, but it is nowhere near as popular of a cartridge for range/target use. The increased popularity of the 9mm leads to a much larger demand, which leads to larger production batches. These large production quantities lead to lower ammo prices for 9mm range/target ammo.

When we look at self-defense loads, however, we see that the pricing is usually very similar between the 380 and 9mm. Self-defense loads are not typically used as range/target ammo, so the demand is not as high for this ammo style. Lower demand leads to smaller production batches which ultimately leads to similar pricing between many 380 and 9mm self-defense ammo lines. 

Summary

Since its first production in 1902, the 9mm has become the world’s most popular centerfire handgun cartridge with no signs of slowing down. With its popularity comes an almost endless number of handguns to choose from, with new designs hitting the market constantly. Ammo choices are almost as plentiful making it easy to find a carry load to fit your needs.

The 380 does not have as many choices when it comes to ammo or handguns, nor does it compete with the 9mm in terms of ballistics, but there is a reason why the 380 is one of the most popular cartridges to carry…… compactness. If you need adequate ballistics in an ultra-compact profile, you would be hard-pressed to find a better cartridge than the 380.

As you have probably gathered, the 9mm is the more versatile option of these 2 cartridges. Then again, you may only be looking for something to carry in your pocket. In which case, the 380 has you covered. Regardless of which cartridge you choose, both are excellent options in their own respects.

*The case capacities listed represent the approximate amount of H2O that will fit inside an empty case. These values can vary based on the manufacturer as different companies will typically result in slightly different case capacities.

--Banana Ballistics