SIG Sauer Mosquito: The SIG that SIG Didn’t Make

SIG Mosquito review
June 11, 2023  
Categories: Guns

Nearly two decades ago, a 22 LR rimfire pistol hit the market that was all metal and branded by SIG Sauer. It was known as the Mosquito, and for many shooters, it appeared to be an unbelievable bargain as a German-made SIG in 22 lr with a sub-$300 price tag. It almost brings to mind, “If something seems too good to be true, it probably is.” Read on for this SIG Sauer Mosquito Review and make your own decision.

Getting The Unicorn

I remember the first time I saw a SIG Sauer Mosquito. It was about 17 years ago. I had just moved to Nevada after a 7-year exile in the gulag known as the People’s Democratic Republic of California. My most recent purchase was a Walther P22 with a threaded barrel. It was a novelty I bought just for the hell of it. It is the type of pistol that is closer to an airsoft pistol than a real one. However, that threaded barrel would have classified it as an “Assault Pistol” in California. No doubt because of all the silencers for sale in the local military surplus store. I was in a small gun shop looking for my next purchase.

“Here’s one for you; I just got 4 of them in from SIG.”, said the shop owner as he handed one to me across the counter.

SIG .22lr review

Outwardly it resembled a SIG P226, only scaled down a bit. More importantly, it felt like I was holding a real pistol in my hand instead of an airsoft gun dressed up to look like a 22. As much as I liked it, I didn’t feel like I needed it at the time. I had a threaded barrel 22-caliber pistol, and I was making up for lost time with new ARs, AKs, and HKs.

After a few years, I noticed that SIG would release different variants of the Mosquito. Mostly different colors like black, grey, OD, etc. I decided I would wait for one that I really liked, and a few years later, it happened.
Another local gun shop was running a customer appreciation sale. I stopped in and actually won a couple of prizes, and then when I looked in the SIG cabinet, I saw my Mosquito.

It sported a multi-cam finish, came with three factory magazines, and included a thread adapter from Silencerco, converting it to 1/2×28 from the factory M9 x 0.75. This one was silencer ready, and I had more than one 22-can sitting in my safe. The fact that it was 30% off due to the sale and included this adapter made it a no-brainer. That was nearly a decade ago, and that pistol has been used to test more than 22 silencers than I can remember. It’s unfailingly quiet, reliable, and reasonably accurate.

SIG Mosquito review


  • Barrel Length: 3.9 inches
  • Overall Length: 7.0 inches
  • Action: Double Action/ Single Action Hammer Fired
  • Capacity: 10 rounds
  • Unloaded Weight: 1 lb. 8 oz.
  • Additional Safeties: Decocker Safety


Buy it and back the bang

Where to Find a SIG Mosquito For Sale


SIG Mosquito Review: Testing the Unicorn

The main types of ammunition that I use are CCI Stingers and Gemtech subsonic. The key takeaway for me was that this is a blowback operated 22, meaning the pistol needs to be cleaned and lubed after every shooting session. The three metal factory magazines are all I’ve ever used, as I’ve heard horror stories about some of the aftermarket polymer ones being failure-prone.

A little after I picked it up, I started to hear horror stories about the Mosquito. It was a jammamatic. It it did not work well with Remington Golden Vipers, or it was the worst gun that SIG had ever made.

All the while, I wondered if I had a unicorn. I may have had one failure to fire out of several thousand rounds, but I blamed that on a single cartridge that was likely a dud.

SIG Mosquito review

In retrospect, I don’t believe my pistol is a unicorn. It was definitely not a so-called “factory ringer” sent to impress a writer, as I bought it over the counter. While I did wonder if maybe I had some special edition because of the finish and the adapter, I later found out that the shop owner just included the adapter to sweeten the deal.

No, the performance of any firearm or any machine, for that matter, breaks down to how you maintain it. We all have those guns that have fired thousands of rounds without cleaning. Sometimes we pride ourselves on that. I used to say, “the only time I clean my guns is when they stop working.”

This goes back to my formal training as a bullseye pistol shooter, where your guns have such tight tolerances that you risk ruining their accuracy by taking them apart. Luckily, I hit a point where I was having issues with firearms that were not performing well, and I took a new look at cleaning and maintenance as a result. There is genuinely a different protocol for different types of firearms. Some require minimal cleaning, but some require a little more than you might think. Blowback 22 rimfire pistols are definitely in the latter category.

SIG Mosquito with Supressor

Back to the SIG Mosquito Review

As mentioned, the SIG Mosquito is a blowback-operated rimfire pistol chambered in 22 lr. It was not made by SIG but was built by German Sport Guns (GSG) for SIG. This is what may need clarification for some people, as GSG needs to be marked on the pistol. However, the font for some of the markings on the barrel is unquestionably identical to what GSG uses.

It is 90% the size of a SIG P226, and the manual of arms is similar primarily. You have the takedown lever followed by the decocking lever and the slide release running down the left side of the slide. There is a manual safety mounted on the slide that requires you to push it upward in order to fire. In the area of the mainspring housing, there is a key lock feature to enable you to lock the pistol to prevent movement of the trigger, etc.

The frame is a polymer with a three-slot integral accessory rail molded in so accessories like lights and lasers can be added. The slide is an aluminum-zinc alloy, and the sights are a standard 3-dot type. There is a magazine safety present, and the pistol will not fire without a magazine in place. Trigger pull is not too bad in either single or double action, breaking at 6.5 and 11 pounds, respectively, and it has a long reset. While it definitely is not a target-grade pistol, you can typically expect groups in the 4-5” pattern at 25 yards.

Mosquito with Knife

Even though it may seem a little overloaded on safety features (manual safety, decocker, magazine safety, lockout, etc.), that is not bad for a scaled-down rimfire pistol, as most of these are bought for young people to learn the basics. A double advantage might be that it could teach a new shooter the importance of maintenance. Unfortunately, the Mosquito does not cotton with left-handed shooters as there is no ambidextrous safety.

I have to give this handgun solid marks on reliability, looks, and of course, it is quiet with a silencer. Its trigger and accuracy are not the stuff of legends but don’t write this one off because Bubba fired nine thousand rounds without ever cleaning it, and when he fished it out of the sea of fast-food wrappers in the cab of his dually, it would not cycle reliably. If you decide to pick one up (or do your own SIG Mosquito review), remember to clean and lube it regularly.

The Mosquito Today

For whatever reason, SIG stopped importing this pistol, and its production as the Mosquito ended in 2015. That was a little after the time I purchased mine. I cannot say if this was due to poor sales, poor QC from GSG, or if SIG was taking their pistol line in a new direction with the P320 line.

Yet, the handgun is still being made by German Sport Guns (GSG) and is imported by American Tactical Imports (ATI) as the Firefly. It still has the look of a classic P-series SIG pistol but no longer has the name.

Although it can be difficult anymore, use quality ammo like CCI Stingers or CCI Mini Mags. Rimfire ammunition is notoriously filthy, and some of the cheaper bulk-packed brands aren’t the best for something like this.

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Mike Searson

Mike Searson

About the Author

Mike “the Mook” Searson is a veteran writer who began his career in firearms at the Camp Pendleton School for Destructive Boys at age 17. He has worked in the firearms industry his entire life, writing about guns and knives for numerous publications and consulting with the film industry on weapons while at the same time working as gunsmith and ballistician. Though seemingly a surly curmudgeon shy a few chromosomes at first meeting, Searson is actually far less of a dick and at least a little smarter than most of the Mad Duo’s minions. He is rightfully considered to be not just good company, but actually fit for polite company as well (though he has never forgotten his roots as a rifleman trained to kill people and break things, and if you look closely you’ll see his knuckles are still quite scabbed over from dragging the ground). You can learn more about him on his website or follow him on Twitter, @MikeSearson.


  1. Charles

    A great gun. I take it with me on hikes in AZ loaded with CCI “pellet” ammo in case of a nasty snake, or to scare off a lion. I clean it somewhat regularly, and have only had jamming problems when I tried a different ammo brand. It is light, quiet, easy to use, reasonably accurate, and cheap to operate.

  2. SIU

    Shut it up.

  3. TGP389

    By the way, I really like that knife in the picture. Care to share it’s geneology?

  4. TGP389

    I hesitate to correct the author, but, per ATI, the Firefly has a zinc alloy frame. The slide is also zinc alloy. I have one in black that I haven’t shot yet, as I just got it last week. It does, indeed feel like a “real” pistol. In fact, for it’s size, I think it’s a little heavier than it would be in all steel. I’m glad to hear such glowing reports about them, because, I, too, have heard all the “jam-o-matic” stories. I based my purchase on the reviews left by buyers on the vendor’s site.

  5. Paul H.

    Really like mine. Has the heft and feel of a full size pistol. My instruction manual said to use only CCI mini mags. No problems with this round, but cycling problems with all lower velocity rounds.

  6. Jim Henning

    Bought one for my daughter probably 10 or 12 years ago- she wanted it instead of tickets to the One Direction concert all of here friends were going. Her reasoning was that it would last longer than going to a concert. She was right. That Mosquito is still going strong today. It’s a great shooter and has more heft to it than the Walther. My daughter said it felt more like a real gun than the Walther 22 did. It was a great training pistol for her and will be a great training pistol for her future children. As for accuracy, it’s a 22 semi auto pistol, not a target pistol. It is accurate for what it is and is a joy to shoot. Never had a malfunction that was the fault of the pistol. Just bad ammo. CCI stingers have always worked best, but it will eat any ammo we put in it.

  7. Mark N.

    I own one. Although I would agree it is great for teaching new shooters, sometimes the excessive safety features get in the way more than they help. Plus it requires a diet of premium high velocity ammo( I always used CCI Minimags) That became very expensive or impossible to find during the Obama administration. Worst of all, the gun is not accurate. I like to shoot small holes in target, and this is not the gun for that task.


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