One of the most highly controversial .22 pistols on the market today in terms of reliability seems to be the SIG Sauer Mosquito. Being the sucker that I am and having a penchant for black bottom feeding pistols, I decided to pick one up to see if all the rumors were true. Lets begin with the exterior.
As it came from the factory:
Seeing how any pistol with a barrel length of less than 105mm instantly makes it an evil baby killer, the Mosquito is only available in Canada as a Sport model featuring an extended barrel of 125mm. Since this looks rather ridiculous on a firearm designed for a 99mm barrel, they include a cover that doubles as a barrel weight which they claim helps you shoot better. All I found was that it made the gun heavier.
They move the front sight forward onto the barrel cover which probably takes away from any added benefit of having a longer sight radius due to the fact that I'm sure the slide never returns to the exact previous position each time you fire. As you may or may not be able to make out, I moved the sight from the cover back onto the front of the slide where I felt it belonged.
The sights are not bad, but they are definitely not designed for target work. The rear is adjustable for windage and the front is replaceable for elevation. It comes with three different sizes and they claim that there is a difference of 20cm at 25m between each size. I found that the tallest sight worked best for me.
Unfortunately, they do not glow in the dark.
Field stripping is quite simple. Using the provided allen key, remove the barrel cover. With the slide closed, rotate the take-down lever 180 degrees so that it points toward the muzzle. Pull the slide back (sharply) and lift. Move the slide forward to remove it fully from the frame.
(we'll get to the shortened barrel in a minute
)
As this is a .22, the barrel is fixed in place as there is no need for it to move. With the slide off, you can easily clean the barrel from the breach and wipe down any powder residue that will have accumulated during firing. I have been using Remington Teflon Dri-Lube and it seems to help keep the powder residue/oil gunk to a minimum.
The Mosquito comes with two recoil springs; a short stiff one for high velocity ammo and a longer softer one for "utility" ammo. (Their word, not mine
) I have found that the stiffer one works best for the ammo I feed it.
One other quick note before I move on; the slide lock is located inside the slide:
Don't ask me why, I just thought it was interesting to note.
The pistol has five (5) different safety systems.
(we don't live in a lawsuit happy society, do we...?)
First off is the obvious one, an ambidextrous slide mounted safety. Down is safe, up is fire.
Second is a hammer block that is only de-activated when the trigger is pulled. (at least this one you don't have to think about)
Third is a magazine disconnector. (kinda annoying but it's not the end of the world)
Fourth is the de-cocker which works just like all the other SiG pistols.
And fifth is an internal lock. There is a small tool included which you use to turn a small tumbler which is found inside the bottom of the grip. If I wasn't paranoid about running into a mis-informed LEO, I'd happily use it in place of a trigger lock... but we all know what would happen if I did.
So yes, here we are at the part where I talk about the shorter barrel.
Doesn't it look way better like this?
It has been reduced in length by an extremely well qualified gunsmith to 106.8mm. If you ever need any gunsmithing done and you want to be sure it's done right, give Gordon a call at Blue Mountain Sports. Best smithing I've seen yet. 
Here is a pic of it with its bigger brother, the NP-34. (ok, so maybe he's adopted)
--------------------
So off to the range we go. Sorry, I don't have any pictures of targets as so far I've mainly been firing it for reliability, not accuracy. Although it's looking like it's going to be an accurate little pistol if it ever finds someone who can shoot it well. (I'm such a lousy shot) I managed to put 10 into about an inch at 7 yards last night, but I'm guessing pretty much anyone can do that at that range. I have been shooting a 3 inch gong and can usually hit it 6 or 7 times out of ten at 15 yards and at least half the time at 20 yards. So it's not bad accuracy wise, but like I said before, the sights really aren't set up for fine tuned target work. This is more of a plinker and maybe a squirrel or groundhog killer if we lived in an area that permitted such activities.
At first I was kinda worried about how it was going to operate as I've heard many stories and opinions that have indicated that this is a very picky pistol when it comes to ammo selection. Well, I have to say, they were right.
So far, the ONLY ammo that it has had no failures with is Remington Thunderbolt. I shot 200 rounds last night of it in a row without so much as a hiccup. Winchester 333 packs are a close second with about one malfunction every other mag or so and don't even get me started on Winchester Xpert. CCI Stingers and Velocitors work very well. The Stingers FTE about one every 25 rounds or so which I blame on the longer case. The Velocitors had no malfunctions but I only had 20 of them to test so it's not really a fair statement to say that they work flawlessly.... yet. I'll let you know if I ever find them for sale in my area again. 
I have a few more brands to try if I can get my mitts on them; I'll report back once (if) I do so.
So yeah, that's the Mosquito in a nutshell. Here are a few more pics in case you're interested:
The dangerous end:
Slide locked back:
Posing with it's (adopted) brother before the trip to the gunsmith:
Just a little 'artsy-fartsy' one that I liked:
If you have any questions or would like pictures of a certain area or part, let me know and I'll do what I can for you.
Thanks for reading!
Matthew
As it came from the factory:


Seeing how any pistol with a barrel length of less than 105mm instantly makes it an evil baby killer, the Mosquito is only available in Canada as a Sport model featuring an extended barrel of 125mm. Since this looks rather ridiculous on a firearm designed for a 99mm barrel, they include a cover that doubles as a barrel weight which they claim helps you shoot better. All I found was that it made the gun heavier.
The sights are not bad, but they are definitely not designed for target work. The rear is adjustable for windage and the front is replaceable for elevation. It comes with three different sizes and they claim that there is a difference of 20cm at 25m between each size. I found that the tallest sight worked best for me.

Unfortunately, they do not glow in the dark.
Field stripping is quite simple. Using the provided allen key, remove the barrel cover. With the slide closed, rotate the take-down lever 180 degrees so that it points toward the muzzle. Pull the slide back (sharply) and lift. Move the slide forward to remove it fully from the frame.

(we'll get to the shortened barrel in a minute
As this is a .22, the barrel is fixed in place as there is no need for it to move. With the slide off, you can easily clean the barrel from the breach and wipe down any powder residue that will have accumulated during firing. I have been using Remington Teflon Dri-Lube and it seems to help keep the powder residue/oil gunk to a minimum.
The Mosquito comes with two recoil springs; a short stiff one for high velocity ammo and a longer softer one for "utility" ammo. (Their word, not mine
One other quick note before I move on; the slide lock is located inside the slide:

Don't ask me why, I just thought it was interesting to note.
The pistol has five (5) different safety systems.
First off is the obvious one, an ambidextrous slide mounted safety. Down is safe, up is fire.
Second is a hammer block that is only de-activated when the trigger is pulled. (at least this one you don't have to think about)
Third is a magazine disconnector. (kinda annoying but it's not the end of the world)
Fourth is the de-cocker which works just like all the other SiG pistols.
And fifth is an internal lock. There is a small tool included which you use to turn a small tumbler which is found inside the bottom of the grip. If I wasn't paranoid about running into a mis-informed LEO, I'd happily use it in place of a trigger lock... but we all know what would happen if I did.
So yes, here we are at the part where I talk about the shorter barrel.

Doesn't it look way better like this?
Here is a pic of it with its bigger brother, the NP-34. (ok, so maybe he's adopted)

--------------------
So off to the range we go. Sorry, I don't have any pictures of targets as so far I've mainly been firing it for reliability, not accuracy. Although it's looking like it's going to be an accurate little pistol if it ever finds someone who can shoot it well. (I'm such a lousy shot) I managed to put 10 into about an inch at 7 yards last night, but I'm guessing pretty much anyone can do that at that range. I have been shooting a 3 inch gong and can usually hit it 6 or 7 times out of ten at 15 yards and at least half the time at 20 yards. So it's not bad accuracy wise, but like I said before, the sights really aren't set up for fine tuned target work. This is more of a plinker and maybe a squirrel or groundhog killer if we lived in an area that permitted such activities.

At first I was kinda worried about how it was going to operate as I've heard many stories and opinions that have indicated that this is a very picky pistol when it comes to ammo selection. Well, I have to say, they were right.

I have a few more brands to try if I can get my mitts on them; I'll report back once (if) I do so.
So yeah, that's the Mosquito in a nutshell. Here are a few more pics in case you're interested:
The dangerous end:

Slide locked back:

Posing with it's (adopted) brother before the trip to the gunsmith:

Just a little 'artsy-fartsy' one that I liked:

If you have any questions or would like pictures of a certain area or part, let me know and I'll do what I can for you.
Thanks for reading!
Matthew
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