October 16, 2023
About 10 years ago, Special Operations Command (SOCOM) realized they had a serious small-arms problem. The Special Operations community shot rifles often, usually with suppressors. The additional backpressure created by mounting a suppressor to the muzzle and trapping gas pushed some of that gas back into the shooter’s face and increased the action’s cycling rate. For a long time, that was seen as an issue that could potentially reduce the rifle’s durability and reliability while also making life uncomfortable for the shooter. SOCOM decided that potential durability and reliability issues could be handled by maintenance. Shooter comfort, however, was not seen as much of an issue.
SOCOM eventually realized that gas from fired cartridges contains seven different metals and three different carcinogens. The thought of pumping harmful gas back into the shooter’s face — especially considering the amount of time that some SOCOM soldiers spend shooting — became a serious problem that needed to be fixed. Blood tests done on SOCOM soldiers showed the presence of these metals and carcinogens, and now everyone knew where those originated. The discovery and the effort to address this issue is what caused the rise of the low backpressure, or “flow-through,” suppressors that we see in increasing numbers today. They are now becoming commercially available and will likely become prevalent for both government and civilian use.
Not Their First
While the Velos Low Back Pressure (LBP) suppressor introduced in 2023 is SilencerCo’s first publicly available low-backpressure offering, it is not the first suppressor of this type that they’ve made. The first SilencerCo LBP suppressor that I heard about was a model sold to a tier-one unit in 2018. A friend of mine worked with that unit and said that they loved those SilencerCo suppressors. When I asked SilencerCo about that suppressor, they indicated that it was a modified Saker designed for a specific application and developed on a compressed timeline. That modified Saker had a baffle stack and a front cap with holes drilled in just the right locations to lower the backpressure. This was a trial-and-error effort that taught SilencerCo’s engineers a lot about how to reduce backpressure while still providing sound and signature reduction.
SilencerCo’s second LBP suppressor was a completely new model done for a Federal Bureau of Investigation (FBI) solicitation. They didn’t win that contract, but the experience pushed the company’s development effort along. When SilencerCo took what they learned from the Special Operations and FBI suppressors, they were well on their way to what would eventually become the Velos LBP.
When SilencerCo looked at the LBP suppressor landscape, it first had to decide on what they wanted the new suppressor to offer. Low backpressure was the number one feature, not only because that’s what the military desires, but also because the commercial market benefits as well. It’s rare that civilians shoot enough suppressed for it to be a health concern, but reducing backpressure also slows a semiautomatic rifle’s bolt velocity. A rotating bolt unlocks and moves rearward slower with low backpressure. Slowing down the bolt on any semiauto rifle reduces wear and tear on the bolt lugs, extractor, and bolt body, especially around the cam-pin hole on an AR-15’s. These are all high-wear areas and common failure points on an AR, so LBP suppressors should be interesting to any AR shooter.
SilencerCo also noticed that other available LBP suppressors suffer from a couple of issues that it wanted to correct. The first? Durability. One of the first flow-through suppressors was created by OSS Suppressors. It worked well enough for most civilian applications, but had a hard time surviving some of the military trials. Another common issue with many LBP suppressors is the hot burning gas passing through them often grabs small metal particles, ignites them, and then throws them out the front of the suppressor. The resulting fireball doesn’t reduce signature but can increase it. Obviously, that was a problem SilencerCo wanted to fix, too.
The final issue SilencerCo wanted to address was the lack of user configurability on any of the LBP suppressors. The consumer had no options for mounts or front caps with these cans. Plus, suppressors often move from one rifle to the next and shooters’ needs change from time to time. SilencerCo wanted to build a suppressor that could accept different mounts and use different front caps.
With the requirements well-defined, SilencerCo began developing the Velos LBP. It began by using 17-4 precipitation-hardened stainless steel for the mount area. They did this for a couple reasons. The first was the durability of this material. Stainless 17-4 machines well and is resistant to the effects of heat and pressure. The second reason is that just about every muzzle device is made from 17-4. It’s important on suppressors that may see hard use to make the muzzle device and suppressor mount out of the same material, or at least ensure that both have the same thermal expansion rate. In cases where this doesn’t happen, the muzzle device heats and cools at one rate while the suppressor heats and cools at a different rate. The result is a can that has to be beat or shot off the muzzle, once the mount is unlocked (obviously).
While the suppressor-mount area is made from 17-4 stainless, the entire body of the suppressor is made from Inconel 625, including the expansion chamber and the baffle. This portion of the suppressor is three-dimensionally (3-D) printed, a marvel of modern manufacturing. Printing in Inconel is a wise choice for any hard-use suppressor.
Inconel is an exotic alloy that is ideally suited for suppressor use. My favorite practical example of Inconel was the cone-shaped exhaust nozzles on the Space Shuttle. Anything that can handle rocket propulsion and penetrating the atmosphere has got to be tough. Not surprisingly, Inconel can handle the heat, pressure, and abrasion that comes with suppressing rifle fire with equanimity.
The decision to 3-D print, or direct metal laser sinter, allows SilencerCo to achieve internal shapes that are impossible with traditional manufacturing methods. Traditional baffles were small cones with skirts that have various cuts in them, stacked on top of each other inside the suppressor body. This method of suppression has been around for more than 100 years! While effective, this type of suppressor has physical limits to what it offers in terms of suppression and resulting backpressure. Now, 3-D printing allows for shapes that were previously impossible to make, so designers have a new canvas on which to paint.
The goal of a good LBP suppressor is to route the gas that it traps away from the muzzle and let it cool before releasing it into the atmosphere. The Velos LBP accomplishes this by using a traditional baffle shape in the center and then forming paths around the center to efficiently route gas. Gas moves in the path of least resistance, so it’ll move down the center until the chambers become pressurized. Then, the gas moves into the paths along the outer baffle edges. The trick is to emplace the direction changes and path twist rates to optimize the time the gas has to cool without creating backpressure. This process took many iterations to optimize, but SilencerCo found its best solution with the Velos LBP. The entire time the gas is moving through the suppressor, it’s moving around the highly durable Inconel.
Inconel also has the advantage of being nonflammable because it resists oxidizing and burning at high temperature. The same cannot be said for titanium or stainless steel. This is one of the reasons why the Velos is so good at signature reduction.
Getting the Velos LBP set up for testing involved disassembly of the mount for inspection. Again, the Velos uses SilencerCo’s “Charlie” mount pattern rather than the popular “Bravo,” or “HUB.” The Charlie is the better of the two designs, even if it isn’t as widely used. The Charlie pattern features a tapered insert for every mount type. This tapered insert gives the mount a lot of engagement surface with the suppressor, in addition to the threads that hold it in place. Tightening the backplate on the suppressor wedges the tapered insert into place. Only deliberate effort can get it unscrewed. This ensures that the mount stays attached to the suppressor, even when using a direct-thread insert. Few things are more frustrating than having the mount unscrew from the suppressor instead of the suppressor unscrewing from the rifle.
Once mounted to an AR-15, I could detect no additional gas coming from the ejection port when compared to unsuppressed fire. Brass ejection was identical whether the suppressor was attached or not to an AR-15 with a non-adjustable gas block. The Velos is also effective at sound reduction and wasn’t uncomfortable without ear protection.
If you look at the SilencerCo website, the Velos LBP measured sound at the muzzle is 137.1 decibels (db). The Saker 556k measured at 136.1 db. That’s not much difference, and it can be surprising that a new suppressor doesn’t perform quite as well as the old. Where the Velos LBP is noticeably better is at the shooter’s ear. Any suppressor that traps a lot of gas at an AR-15’s muzzle will push more gas out of the ejection port, a phenomenon known as “port pop.” This is quantifiable when the sound metering equipment also measures sound at the shooter’s ear. If you want the quietest suppressor for the AR-15 shooter, the Velos LBP is it.
The Velos LBP is the lowest backpressure suppressor SilencerCo has ever made. It is also the most durable suppressor they’ve ever made. It is the only suppressor I’ve known to carry a full-auto rating with no barrel restrictions. That’s a bunch of firsts that every AR-15 shooter can appreciate.
SilencerCo Velos LBP
- Caliber: .22/5.56mm
- Diameter: 1.73 in.
- Thread Pattern: SilencerCo Charlie
- Overall Length: 5.98 in.
- Weight: 15.2 ounces
- Finish: Cerakote
- MSRP: $1,174
- Manufacturer: SilencerCo, 801-417-5384, silencerco.com
Enjoy articles like this?
Subscribe to the magazine.
Get access to everything Guns & Ammo has to offer.
Subscribe to the Magazine