I'll open by saying that the Mosquito is sort of like that girl you have the hots for, but you know she is nothing but trouble and is going to put you through hell, but you still end up chasing the skirt.
I picked up the Mosquito as my first handgun and have spent an incredible amount of time reading and researching on it. I ended up deciding on it over several other popular 22lr handguns. The reasons will become clear later.
The Mosquito has some advantages and disadvantages. Depending on what you are looking for, the disadvantages may outweigh the advantages and vice versa.
The Mosquito has one major distinct disadvantage: The gun is *very* picky with ammunition.
The gun comes with two recoil springs, one softer / longer, and one shorter / stiffer spring.
Shooting "regular" ammo such as the Fiocchi or hotter ammo such as CCI Velocitor, you need to use the softer / longer return spring, otherwise the Mosquito will simply not cycle properly.
Strangely, the choice of ammunition also effects the mags, in the sense that the way that the rounds stack and feed from the mags they can stick or get misaligned a little.
With all of the ammo I was putting through it, the Mosquito was very unhappy and unreliable.
FTC and FTF at least once a mag.
Depending on your temperament, this can become very aggravating very quickly.
Then my box of CCI Mini Mags arrived.
The Mosquito changes character once install the shorter / stiffer spring, and put on the tallest front sight and start shooting the Mini Mags.
The only way I can describe the incredible change is that Sig probably designed the Mosquito around the CCI Mini Mag round.
The ammo feeds, the gun shoots, everything is proper, just how you would expect. The gun finally comes into it's own.
The model I have is quite accurate (extended barrel sport model), but you have to work at it.
Tonight we cycled 600 Mini Mags through it and it did really well as my personal skill improved with the weapon. By the end of the night we were often shooting 1" groups at 15 feet. Please remember that I'm a new shooter
I know its not stellar compared to something like the Rugers that many people have, but it's not engineered to be a purpose built target pistol like the Rugers.
There's a few items that I feel were important in my decision in getting the Mosquito.
The Mosquito is very similar in looks to a regular pistol. This might seem vain, but it's actually important in that it doesn't just look the part, but also functions the part.
All the controls are very similar to that of a full size p226. A new shooter could use the Moquito and transition to something bigger with a p226 with very little relearning. This follows through with things such as take down and maintenance.
When you take a take down a Ruger target pistol for the first time, it's a little freaky. Maintenance of the Mosquito is very simple, and very similar to the p226s.
The other major factor for me was weight. The mosquito weighs only 10% less then a base model p226. When you are practicing a lot and burning ammo like crazy, it helps to have something that won't break the bank, but at the same token remains very similar in weight and controls.
When you transition back to a full size pistol like a p226, I believe a lot of that practice and familiarity is retained.
The points noted here greatly influenced my decision on purchasing the Mosquito. I don't have enough time behind the trigger to be able to say if I have made the right decision yet, but after putting the CCI Mini Mag trough her, I am completely satisfied with the purchase.
Apologies for making this so long, but I hope it is more informative then some others in the thread saying that the Mosquito is a terrible gun without being able to identify why, or how to correct it.
I hope that whatever you end up getting you enjoy and get the most of it.
Good luck.
