Sig Mosquito misfires & jambs
- Thread starter Roadhunter
- Start date
Sell your Mosquito and buy a .22 handgun that is build around performance rather than tacticool looks, such as a Ruger or a Browning. That's just my 2 cents, so please don't be offended if you lover your Mosquito and have no desire to part with it... 
Like Krausb said, maybe think about getting a dedicated .22. I just recently got a MkIII hunter and I love it. Feeds everything (except AE, mag doesn't like them)... If not then stick with any CCI's if you haven't tried them yet.
Harrier .45
Regular
- Location
- Ontario, north of Toronto
The SIG Mosquito is notorious for demanding only high quality, high velocity .22 LR ammunition for peak performance. This means regular Standard velocity ammunition such as Remington Target, Eley Club, etc. will not function properly in the Mosquito. The most common occurrence with regard to jamming is that the slide will travel rearward far enough to eject the spent casing, but not far enough to properly strip the new round from the magazine, causing the fresh cartridge to "reverse nose-dive" into the top of the breech and jam the gun.
In addition, the Mosquito is somewhat snobbish in that it must be kept extremely clean --- that is no carbon build up in the slide or on the frame rails as this may cause excessive friction that will slow the slide down and not allow the fresh round to seat fully into the chamber with the proper velocity of the slide to press it into place.
We have heard that the Mosquito seems to work well with some of the following brands of ammunition (as well as a few others not listed here):
CCI MiniMag
CCI Velocitor
Remington Golden Bullet
Remington Viper
Remington Yellow Jacket
Winchester Super-X (40 grain)
It has also been reported that the Mosquito prefers heavier bullets in the 40-grain range over the lighter 3x-grain loads.
In addition, the Mosquito is somewhat snobbish in that it must be kept extremely clean --- that is no carbon build up in the slide or on the frame rails as this may cause excessive friction that will slow the slide down and not allow the fresh round to seat fully into the chamber with the proper velocity of the slide to press it into place.
We have heard that the Mosquito seems to work well with some of the following brands of ammunition (as well as a few others not listed here):
CCI MiniMag
CCI Velocitor
Remington Golden Bullet
Remington Viper
Remington Yellow Jacket
Winchester Super-X (40 grain)
It has also been reported that the Mosquito prefers heavier bullets in the 40-grain range over the lighter 3x-grain loads.
I noticed the op stated that the gun is worse in cold weather.I am having the same problem with a new STI 9mm.As the gun get's colder and colder it get's to the point that i cant even practice.I dont practice outside this time of year but right now i need to.Could the problem be semi auto's dont like the cold?Just asking because i to am getting frustrated.
I've been intrigued by this Sig Mosquito for some time. It would make an excellent pistol for my kids to learn with. How exactly is it jamming for you guys? Is it failing to extract or feed or does it stove pipe or what....???
Not my Ruger Mark 2
Not my buddys SW semi,
Can put the best ammo all the way down to Federal Bulkpacks and shoot all day long with no jams.
You cant compare the 'fussiness' [read bad design] of the Mosquito to the occasional 1/100 shot stovepipe real rimfire pistols experience. Its tried and true comparison of apples and oranges.
It's a nice little gun and has a great look and feel about it,but what the others have stated it is very fussy with ammo and you need to clean it ! I have been using the cci mini mag's in reg and HP, work like a charm
Roadhunter
New member
Mine doesn't eject the empty all the way and tries to stuff another one in. Sometimes the firing pin either doesn't strike it hard enough or it's a dud. It did come with another lighter spring that I haven't tried yet. I always clean it after every time out too.
