A Review Of The Sig Sauer Mosquito

A while back, I promised @Phases and @EarlyMon that I would put out the occasional in-depth review on some of my favorite rifles, shotguns and handguns. So without further ado, here’s my first, on the Sig Sauer Mosquito pistol. Y’all be gentle please, I’m new at this. Constructive comments are welcome as are corrections and mo’ data.

Facts And Figures

The Mosquito is one of two Sig Sauer dedicated .22LR handguns. The pistol covered in this review is the standard black Mosquito without a threaded barrel, Sig Sauer model number MOS-22-B. MSRP on this version, at this time, is $408 US. If I remember correctly, I paid $369 for mine at one of the large chain sporting goods stores. Purchased new, the Mosquito comes in a foam-lined formed plastic case, with a manual, lock and key, 2nd magazine and a second recoil spring (more on that later).

The Mosquito is very much like, and at the same time very much unlike almost all other lines of handguns offered by Sig Sauer. The differences show in three ways. First, the Mosquito is not made by Sig. Like Sig’s other .22LR offering, the 1911-styled model, number 1911-22-B, it’s made by GSG (German Sport Guns,) Secondly, the barrel is solidly, permanently formed into the frame. And lastly, the Mosquito is a 7/8-size version of the P-220/226 series. In fact, here are the numbers on the li’l guy, straight from Sig’s website:

Action Type DA/SA
Overall Length 7.2 in
Overall Height 5.3 in
Overall Width 1.5 in
Barrel Length 3.9 in
Sight Radius 5.5 in
Weight w/Mag 24.6 oz
Mag Capacity 10 rounds
Sights Adjustable Rear
Grips Black Polymer
Frame Finish Black Polymer
Slide Finish Blued
Trigger Pull DA 14 lbs and SA 7 lbs
Accessory Rail Yes

Styling on the Mosquito is very similar to Sig’s acclaimed P-series handguns. The breakdown lever, slide release, de-cocking lever and the magazine release are all laid out like its big brothers. Anyone familiar with one of the P-series could pick up a Mosquito and go to work without any surprises with regard to where the buttons are located. The safety is slide-mounted and ambidextrous. The rear sights are adjustable for windage only, and are yellow dot front and rear. They are not night sights like Trijicon or Mepro. The webpage shows the slide finish as blued steel, but the downloadable data sheet from Sig shows correctly that this is a Nitron-finished steel slide.

To The Bench

Fit and finish are good-to-very-good when compared to other poly .22LR semi-autos. The action of the slide is almost glassy feeling. It’s very smooth and a reasonably light amount of muscle is needed to rack it.

My scale is having issues so I can’t verify the weight, but seat-of-the-pants it feels about right at 25 ounces.

My trusty Lyman trigger strain gauge only registers to a maximum of 12 pounds pull so I can’t quantify the SA trigger pull, but there again 14 lbs feels about right. I’m not real thrilled with the SA part of the program as it’s almost too heavy for a pistol of this nature The DA pull, averaged over 10 tries worked out to 7 lbs, 7 ounces with a high of 7 lbs, 12 ounces and a low of 7 lbs, 3 ounces. The DA pull is fairly long at about 3/8” but it’s consistent and once you are familiar with the weight and the break point, there’s no problem shooting accurately with it.

The sights are quite useable even though they aren’t night sights. I don’t consider this pistol a self-defense weapon so that’s a non-starter for me. The yellow dots are easy to pick up, front and rear. The sight is pleasantly tall and the gap between the vertical edges of the rear sight and the vertical edges of the front sight is wide enough to be visible but not so much to make centering the post difficult. This sight coupled with the low recoil of the .22LR round make for quick re-acquisition of the target and placing follow-up shots.

Disassembly is simplicity itself. Cock the hammer, rotate the takedown lever 180 degrees and push the slide toward the hammer while gently lifting up. The slide will move past the alignment grooves and then the rear will lift up away from the frame. At that point push the slide forward and it will come completely off the frame. The recoil spring and guide rod will both come free at that time. That’s it for field stripping – four pieces, no fuss, no muss. Re-assembly is a simple reversal of that with one important thing to note: The recoil spring should be oriented with the large- diameter end facing toward the front sight with the narrow-diameter end towards the trigger. I don’t know why this has to be, but it does make a difference in the successful feeding of ammunition. I found this out myself after a frustrating session.

There is a fifth piece that you may note from the photos. It’s loose but captive, trapped between the bottom of the barrel and the frame. It’s a silver T-shaped piece that functions as a seat for the recoil spring guide rod. Just make sure it is seated all the way into the fitted base between the barrel and the frame. Why is it like that? Again, I don’t know. It’s just worth mentioning.

Cleaning is straight forward and doesn’t require any heroic measures or special tools. My normal kit is Hoppe’s #9 for cleaning, M-Pro7 for lube, and a bore snake for quick swipes on a long day of shooting. I do find a set of Tipton’s cleaning picks to be helpful getting to some of the smaller nooks and crannies.

Slingin’ Lead

At the handgun range I generally shoot 7-yards, 10-yards, 15-yard and if I’m feeling lucky or just wanting to push things I’ll shoot the 25-yard setup. I find the Mosquito to be consistently accurate as long as I do my part properly. Theoretically, with the solid-mount barrel the bullet should go to the same spot every time if your aim, grip and pull don’t change. Yeah well, that’s all I’m going to say about theory. :) In reality, on a good day for me I’ll generate 10-round groups of 3”-4” inches at 7 yards. 5”-8” at 10 yards, and past that I just try to keep it in the 9-ring. That’s shooting from a two-handed standing position, at a slow fire rate of 1 round every three to four seconds. Perfectly suiting the week I had, my attempts to do this with a camera present failed miserably yesterday. I’ll keep at it until I can post some images that are not totally embarrassing.

The ergonomics of this pistol are excellent. It fits my hand like it’s customized for it. The balance is just about perfect with no barrel drag or heavy grip sensations to distract you. The magazine release and the slide release are both positioned so that I don’t have to reposition my hand to operate either of them. The decocking lever? Not so much, but if you are using it, then holding on target isn’t an issue at that moment.

Being a .22LR pistol, recoil is minimal. Re-acquiring the target and putting fast follow-up shots down range is easy, comfortable and also non-intimidating for young or first-time shooters.

As you may have heard, the Mosquito can be a very finicky shooter, especially for the first 500-1,000 rounds. It does state in the owner’s manual that it was developed to shoot the CCI Mini-Mag high-velocity ammunition. Mine has run a little over 1,000 Mini-Mags flawlessly, but has had some FTF’s (guessing 25-30) with a 375 count box of Federal Gold Medal. Both of these are 1,200 FPS rounds. Stepping down to Remington Golden bullets was a fiasco. Maybe, maybe, maybe 50% of the 100 I tried were able to feed, fire and eject properly.

There is a caveat to this, however. The Mosquito ships with two recoil springs, one for HV rounds and one for standard-velocity bullets. At this time I haven’t tried swapping the springs and running the poorer performing brands through the pistol again. Frankly I enjoy it so much as-is that I prefer to hunt down CCI Mini-Mags for use rather than shoot the other stuff. But, more to come on this as time permits.

Other Mosquito owners that I’ve talked with, posted with and read about on the ‘net report widely varying degrees of satisfaction. Some have zero issues with ammo at all, the majority seem to fall in my category as stated above, some have issues with anything they feed the beast at first and then it gets better, and a small number can’t get it to function regardless of what they try. Your mileage may, and probably WILL vary. One practice to make a note of is to place a drop of lubricating oil in the tiny hole on the right side of the slide every 150-200 rounds during a session. I’ve run 300 through in one heavy session without any added lube and had zero issues, but it mentions this in the owner’s manual.

Odds And Ends

Extra Sig Sauer magazines are expensive if you can even find them. The MSRP for one is $46! I was fortunate in that the sales guy gave me an opportunity to buy the one extra he had in stock at store cost when I purchased the pistol. I recently stumbled across a website that has their own magazine for the ‘Skeeter. It is indistinguishable from the Sig produced one and feeds flawlessly. It’s also only $20! Keep Shooting Mag

Short Version

I enjoy this little pistol a lot. It’s relatively light with a decent trigger, and if you have the ammo issue sorted it’s inexpensive fun that’ll last you for years!


Leave a Reply

Your email address will not be published. Required fields are marked *