When selecting the best 9mm ammo, terminal performance is important, but 100 percent reliability is critical -
Selecting the best 9mm ammo for your defensive handgun is important and there are a variety of decisions to be made.
You must choose a brand of ammunition, a style of bullet, the velocity of the bullet, and the weight of the bullet.
All these things will directly relate to the reliability of the ammunition in the handgun you’re relying on for personal protection.
While the terminal performance of the ammunition is important—and mostly dictated by the bullet style, velocity, and weight—reliability is more important.
Reliability is King
Terminal performance is a subjective thing.
Some will argue that penetration trumps bullet deformation/expansion, others will argue the opposite, and some will seek a certain degree of balance between both when selecting the best 9mm ammo.
Reliability on the other hand – at least in your defensive handgun – is utterly objective. The ammunition either does or does not work without fail.
Bullet weight can sometimes have a bearing on reliability in pistols and revolvers, but the answer to that question is one that’s easy to obtain.
You simply must test the ammo in your firearm.
Bullet Weight and Terminal Performance
Terminal performance in the best 9mm ammo, which directly relates to the way a particular bullet deforms, penetrates, and damages tissues, is a separate concern from bullet weight.
Bullet weight does not have as much to do with the terminal performance of defensive handgun ammunition as one might think.
This is because most defensive handgun loads – regardless of bullet weight – are crafted to perform within the guidelines established by the FBI.
That means bullet deformation/expansion to about 1.5 times the original diameter and penetration to depths between 12 and 18 inches, when tested in 10 percent ordnance gelatin.
For example, typical 9mm Luger bullet weights are 115, 124, and 147 grains.
The Gold Dot bullet is well regarded as one that delivers good terminal performance, and Speer offers standard pressure, 115-, 124-, and 147-grain, 9mm loads with this bullet.
Assuming all three of these loads will deliver 100 percent reliability in your pistol, from the shooter’s standpoint, recoil will be the only difference.
The 124-grain load will recoil with about 4 percent more force than the 115-grain load, and the 147-grain load will have about 7 percent more force.
Different Bullet Weights, Same Penetration
Terminally speaking, penetration depths will vary between these bullets in the best 9mm ammo by only about three-quarters of an inch, and bullet upset, deformation, or expansion, by only about 10 percent.
Maybe the best way to compare the terminal performance between these different bullet weights is by looking at what is often called the crush cavity.
This represents the size of the hole made by the bullet, based on its deformed frontal diameter and the depth of penetration.
Comparison in this way shows a crush cavity of 3.07 cubic inches for the 147-grain bullet, 3.72 cubic inches for the 115-grain bullet, and 4.06 inches for the 124-grain bullet.
This difference is not small.
If you compare the 147-grain bullet crush cavity to the 124-grain bullet crush cavity, the 124-grain bullet’s crush cavity is 32 percent larger.
For those familiar with terminal ballistics this is not a surprise, given that with most centerfire pistol and revolver cartridges, and even rifle cartridges the best balance of terminal performance is often found with middle-of-the-road bullet weights.
It’s a “Goldilocks” kind of thing; one it too light, one is too heavy, and the other is just right.
Barrel Length and Ammunition
One final consideration is handgun barrel length.
With extremely short barrels, velocity is limited, and in most cases lighter bullet weights will deliver a better balance of terminal performance at lower impact velocities.
This is of course why some manufacturers offer ammunition specifically designed for short barrel handguns.
Keep all this in mind when selecting defensive handgun ammunition. But remember, reliability is still the most important thing, and that’s a topic for another time.