Thunder Beast Arms Fly 9 Pistol Suppressor: Field Tested

The Thunder Beast Arms Fly 9 is a lightweight and compact 9mm suppressor that offers two different length options for suppressed shooting.

September 29, 2023 By Patrick Sweeney

When it comes to suppressors, a lot people want a 5.56, because, well, that’s what the SOF/SEALs/SpecOps/Operators use, right? Most people who are paying attention go for a rimfire one at first, because they are less expensive, and ammo is, oh, less expensive. But the real volume of ammo consumed, and the number of firearms out there, fall into the “nine-mil” category. That is, nine millimeter pistols and pistol-caliber carbines. Judging by the empty brass carpeting my local gun club range floors, either everyone is shooting 9mm, or those who aren’t are industrious in picking up their brass. It has gotten so bad if I plan on shooting something other than 9mm, and want to save my brass, I either take a tarp or rake the range clean before I start shooting. So, a 9mm suppressor makes a lot of sense.

Enter the Thunderbeast Arms Fly 9. The idea was simple: make a 9mm silencer that was lightweight, could be compact, durable enough to work on other calibers, and oh, easy to clean. This means it is really effective, efficient, but it does come at some cost. In the grand scheme of things, the price is more than reasonable, but someone out there is going to say, “Mine is almost as quiet, and a couple of hundred bucks less in price.” Good, go and have fun. The Fly 9 is made out of titanium, except for the booster which is stainless steel. That’s one way to make it light, and if you want durable, then you go with titanium instead of aluminum.

thunger-beast-fly9-02 — The Fly 9 threads right onto the barrel of your pistol, provided it has an extended, threaded muzzle.

The boost is the spring-loaded portion, the rear assembly, and it allows you to bolt just shy of eight ounces of extra weight onto your pistol barrel, and have it still function. The spring loads up during recoil, then springs back, delivering its stored energy to the pistol, and cycling the action. This has the curious effect of making a heavier pistol seem to recoil sharper than without the suppressor. All booster-equipped silencers do that, so nothing new here. The booster is threaded to the standard 9mm pistol barrel threading of 1/2x28, which may or may not fit onto various PCCs. The old Colt submachine guns and 9mm PCCs were threaded 1/2x36, so if you have one of those you may have to do some searching for a rear mount or an adapter/thread converter. The rear of the Fly 9 body is threaded 1.125" x 28, which is also what SilencerCo uses, or Kaw Valley Precision, so you can use one of their rear caps to go to a PCC, including a tri-lug like the old HK MP5 mount.

I can see the gears turning on some of you. “1/2x28, eh? How about my AR-15?” Well, if you want to use it on a 223/5.56, this is not going to go well. TBAC does not recommend it for that, so don’t do it. However, there are other options. How about .300 Blackout, or .350 Legend? Yep. Now, there are barrel length restrictions on those, so pay attention. If you are running .300 blackout supersonic, you will have to have a barrel length of no less than eight inches. If you are running subsonic loads, then a five-and-a-half-inch barrel will be long enough. And you .350 Legend shooters? A sixteen-inch barrel is what you will need to stay within the TBAC recommendations. I don’t see any of those being a problem. .300 Blackout pistols and SBRs are likely to have an eight-inch barrel anyway. And someone hunting with a .350 Legend is going to be using a sixteen-inch barrel. One interesting detail in the length restrictions is .357 Magnum. You have to have a four-inch barrel or longer here. OK, someone find me a self-loading pistol in .357 Magnum, let alone one with a barrel shorter than four inches. Anyone? Bueller?

The exterior is done up in a Cerakote finish, your choice of Black, OD Green, or FDE. The cool part is the Fly 9 is adaptable. The line, just past halfway down the length? That’s the join, where the front portion is screwed into the rear (mount) portion. The two together bring it to the seven inches and almost eight ounces point. And, the quietest and most effective in decreasing noise. But, if you do not want to have a full-length suppressor, you can unscrew the front portion, remove (unscrew) the front cap from it, and screw the front cap into the front end of the rear portion. You now have a suppressor that is only 4.4-inches long, and 5.5 ounces in weight. It is, of course, less quiet, because, well, there’s less there to do the work.

Why do this? Because you want something more compact. Usually also in conjunction with a subsonic 9mm load, so you aren’t giving up that much in the way of quiet. Ok, what if you just want the compact one? Can you buy the compact (rear) portion, and then later, add on the front portion? Nope. Not because TBAC is being obstinate, but because the federal regulations don’t allow it. You can make your silencer less effective (going from long to short), but you cannot make it more effective later on. Stop shaking your head, yes, it is inane, but those are the regs, so get used to it.

thunger-beast-fly9-03 — The Fly 9 comes with a filler that keeps the booster from boosting, if you use it on a firearm that doesn’t need boosting. The baffles of the Fly 9 are secured in place and have turbulence slots in the entry port.

Opening up the Fly 9, the baffles are secured in place, and each baffle has a gas turbulence inducing cut in the entry port. More turbulence means more quiet, so that’s good. But the baffles don’t come out? How are you supposed to clean it? Well, TBAC recommends that you weigh your Fly 9, and if it weighs more than one ounce greater than brand-new, clean it, or every 500 rounds. Cleaning is actually simple. Remove the rear cap and the booster and spring. Use CLR (yes, the household stuff, at big-box stores) and plug the front cap clearance hole. Fill up the Fly 9 with CLR and leave it overnight. If you have an ultrasonic tank, pour the CLR out and run the Fly 9 in the tank (not with CLR, that’s bad for your ultrasonic cleaner) and alternate until the extra weight goes away. Oh, and wear rubber gloves, the CLR/suppressor gunk is nasty stuff. That’s it, no brushes, no patches, no big deal. Now, if cleaning your Fly 9 is just too much, and you’re willing to pay the shipping, TBAC will clean it for free once a year.

To test the Fly 9, I pulled a host out of the safe, a CZ P10 Compact, with extended barrel and suppressor sights. The Fly 9, being a tenth of an inch under an inch and a half in diameter, made the CZ sights tall enough to use as sights, instead of aiming through the suppressor, as I’ve learned to do with normal-height sights. As expected, the P10 felt a bit more “jolty” with the Fly 9 on that without. Once you learn to feel recoil, you can tell that there’s a two-part ker-chunk to it, kind of like shooting an Auto-5. But, all booster-equipped suppressors do this on pistols, and that’s nothing unique to the Fly 9. I tested the Fly 9 for point of impact shift, and did not see any. It has been a long time since silencer makers dealt with that, and I’d be surprised if any new suppressors showed a shift. But, I test anyway.

thunger-beast-fly9-04 — The Fly 9 comes in two parts; with a front cap you screw on to whichever length you are using.

It was really quiet full length, and less-so in the short mode. Just on a whim, I tried the short mode, with the fixed spacer installed (no boosting being done) just to see if it would cycle. Well, it did a few times, but my shooting grip is vise-like, and if yours isn’t even stronger than mine, it won’t work for you. I could get it to cycle half the time, but it isn’t something I’d count on. In metering, the test ammunition, SIG 115 FMJ (what I had a lot of when I went to the ammo bunker) produced the expected 161 dB in the “just a pistol” mode, no Fly 9. With the full Fly 9 on, the combo posted an impressive 129 dB. The short mode, just the rear portion, was 137 dB, which is on the edge of hearing-safe, but not good enough for me.

I’ve spent a long time protecting my hearing, and while there are those who feel 140 dB is “hearing safe” I’m, more comfortable using 135 dB as that threshold. The full-sized Fly 9 is, and I’d bet that some testing with subsonic 9mm loads (not all loads are equal) the short mode could be made hearing-safe by my standard. So, if you want light weight, adaptability to different lengths, usability on different calibers, tough as hell and quiet, the Fly 9 needs to be on your short list, if not immediately on your shopping list.