Hornady Subsonic Ammo Review

Hornady's Subsonic ammo cuts the noise but still delivers the performance.

December 11, 2020 By Keith Wood

I’m not sure who deserves credit for the explosion in suppressor popularity in this country, but there is little doubt of its occurrence. Suppressors are regulated by the National Firearms Act, which means that every transfer must be approved. If we dive deep into the data published by BATFE in 2017, we can see that the number of Form 4 transfer applications went from 7,024 in 1990 to 133,911 in 2016.

Since there have been a fixed number of transferable machine guns since 1986, it is a safe assumption that the vast majority of those Form 4 applications were for suppressors. So how many suppressors are actually out there? According to the American Suppressor Association, the number stood at 1.8 million as of January.

The rapid growth in suppressor ownership left a gap in the ammunition market, i.e., the widespread availability of quality subsonic ammunition designed specifically to work at such low velocities. With few players doing it right, Hornady stepped in and built its Subsonic line of ammunition to meet the demand.

I grew up in a home with a pretty healthy collection of firearms—and among them was a handful of suppressors. Because of my long experience with them, I knew few were as quiet as those you saw in the movies. Unless it was a suppressed subsonic .22 rimfire, it still sounded like a gunshot.

A suppressor works by temporarily trapping propellant gases inside a system of baffles, effectively flattening the curve of muzzle blast and, therefore, sound signature. Think of it as a muffler for a firearm.

But here’s the rub: Unless subsonic ammunition is used, even a suppressed firearm will produce a sonic “crack” as it moves through the air. The muzzle blast is far less pronounced near the shooter, but the overall sound signature is still loud.

If you’re a soldier trying to quietly take out a sentry or a rancher hunting a group of feral hogs, this additional noise could mean the difference between success and failure. The solution to this problem is simple: ammunition that doesn’t create a sonic signature because it is moving at less than the speed of sound. Bullets reach supersonic speeds at around 1,130 fps at sea level with a temperature of around 70 degrees. Therefore, in order to be reliably subsonic, a load must have consistent velocities of less than 1,100 fps.

Various loads have been used in suppressed firearms since suppressors came into common use in World War II and on into more modern times, but it wasn’t always ideal for its intended use (see sidebar). That started to change in the 1970s and ’80s when the 9mm submachine gun was the go-to weapon for counter-terrorist troops and 147-grain subsonic jacketed hollowpoint ammunition became more widely available.

There was still a problem, though. Not all pistol bullets are designed to expand reliably at subsonic velocities, which often left terminal performance lacking. This problem was more pronounced with rifle ammunition, but handguns were not immune.

When civilians began shooting suppressors over the past decade or two, they also recognized the lack of performance of many subsonic loads. The answer couldn’t be higher velocities, which meant the solution had to be bullets that would expand more readily. When Hornady set out to produce its own subsonic ammo, it specifically chose bullets that are designed to expand at slow speeds.

Hornady launched its Subsonic products in 2018 and added handgun chamberings in 2020. Hornady’s handgun line of Subsonic ammunition contains three loads for three different cartridges: a 147-grain 9mm, a 180-grain .40 S&W and a 230-grain .45 ACP.

Each of these loads uses Hornady’s proven XTP (eXtreme Terminal Performance) jacketed hollowpoint bullet. These bullets were no doubt chosen because they were already designed to expand in these muzzle velocity ranges since the company’s 147-grain, 180-grain and 230-grain loads fit into that envelope.

My two centerfire handgun suppressors are an older 9mm from DeGroat Tactical Armaments and a SilencerCo Osprey 45. The DeGroat suppressor’s 1/2x28 threads matched both 9mm barrels, while the Osprey is user-configurable to a variety of different thread patterns using its interchangeable piston system. Because of this, I was able to mount the Osprey on both the .45 and 9mm handguns.

In case you’re wondering, it is perfectly fine to use a .45 suppressor on a 9mm, and there is no loss in sound-reduction performance. But here I want to make the point that while subsonic ammunition is hypothetically quieter than supersonic issue in any given firearm, there is no noticeable difference in terms of the report unless a suppressor is used.

In other words, don’t think you can fire an unsuppressed firearm with subsonic ammo without seriously damaging your hearing (or disturbing the neighbors).

Suppressors also cut recoil and muzzle blast, making them physiologically easier to shoot well, and they add weight and stability to the firearm. Because of these attributes, particularly the reduction in muzzle blast, suppressed firearms with subsonic ammunition are a great tool for coaching new shooters.

According to instructor and prolific inventor Bill Rogers, who has given the issue careful study, flinching is often caused by the overpressure event of propellant gases reaching the shooter’s eyes. This causes an involuntary response a suppressor can eliminate. Rogers traditionally used a gas mask to coach shooters out of a flinch, but a suppressor is a more comfortable solution.

Accurate sound-measuring equipment is cost-prohibitive for average folks like me, so I can’t list the actual reductions in sound using Hornady’s Subsonic ammunition. SilencerCo’s data, which I trust are correct, list average muzzle report measurements of 125.2 dB for 9mm and 131.3 dB in .45 ACP using the Osprey 45 suppressor.

For comparison, OSHA’s “hearing safe” threshold is 140 dB, so all of these loads should fall into that category when using a quality suppressor. Keep in mind that the decibel scale is logarithmic, not linear.

From a practical but subjective standpoint, both loads I tested were consistently quiet when used in my suppressed pistols. I’ve shot plenty of suppressed centerfire handguns, and these loads were, to my ear, as quiet as any.

There is a common myth that suppressors decrease the velocity of a given load, which is probably a throwback to the days of suppressors using wipes instead of baffles. I have found the opposite to be true, and in each case here, the suppressed velocities were appreciably higher.

Consistency in velocity is very important in this context because a significant extreme spread could mean that individual shots might be supersonic, thereby creating a significantly greater sound signature. Hornady’s Subsonic ammunition maintained a comfortable average velocity that kept every shot well below the subsonic threshold. In fact, none of the 100 or so rounds I fired moved at greater than 1,000 fps.

Accuracy was evaluated by shooting at a 25-yard target from a sturdy benchrest. When discussing accuracy, I should make it clear right away that two out of the three guns I used did not have suppressor-height sights or an optic. The Osprey 45 is a low-profile design that puts most of the suppressor bottom below the bore, but it still partially obscured my view of the target with both Glocks, so take the suppressed accuracy results with a grain of salt.

That wasn’t the case with the Fueled By Ed Brown MP-F3, which had both a Trijicon SRO optic and tall iron sights that gave me a clear view of the sight picture and the target.

In my experience, handguns are almost always more practically accurate with a suppressor attached, probably because they make humans less scared of muzzle blast. As I’ve come to expect with Hornady’s XTP bullets, accuracy was excellent, with one exception.

Five-shot groups from both the Fueled By Ed Brown MP-F3 and the Glock 19 hovered right around the two-inch mark at 25 yards, with both guns shooting slightly better with the suppressor attached.

The Glock 21 fired five-shot groups that were almost identical with the suppressor, but with the Osprey 45 removed, groups opened up to six-inch patterns. I’m not exactly sure what to blame, but other than the shooter, my first culprit would be the aftermarket barrel. Perhaps not coincidentally, the slide on the Glock 21 failed to go into battery more than once.

Based on the accuracy and reliability I saw with each other gun/load combination, I’m confident that the ammunition was not at fault for either the poor accuracy or spotty reliability. Interestingly, the worst groups of the day showed the lowest standard deviation in velocity, more evidence the ammo wasn’t responsible.

Barring legislation that would deprive us of them, suppressors are here to stay. To maximize the performance of a suppressor, subsonic ammunition is a must. Hornady’s Subsonic line of ammunition correctly matches the components to its velocity to ensure that the loads are both quiet and terminally effective. Quality and consistency is typical Hornady, which is to say excellent.