Review:

The SIG/SAUER Mosquito is a fantastic handgun. It is sized at 90%-scale to the SIG P226 9mm, which makes it an obvious training weapon for any full-sized duty sidearm. The fact that it fires still-inexpensive .22LR ammo makes it a weapon that will be fired much more than anyone's Duty Gun. All of the features of a full-sized SIG weapon are on this handgun, so training on this one translates to a 9mm or .40S&W or .45ACP, without the recoil or ammunition expense.

The Mosquito's manual specifies that there are just two ammunition types that it was built around, so don't deviate from the engineer's specs. It comes with two slide springs; one for CCI Mini-Mag rounds, and one for Remington/Eley subsonic rounds. If you buy some cheap .22LR ammo from a Big Box store, and the weapon does not not function properly, blame yourself. There are just two types of ammunition that this weapon was built around, so use them.

The default slide spring is designed for the CCI Mini-Mag ammunition. The Mosquito has a standard-weight slide, similar to a P226 9mm slide, so the recommendation of Mini-Mag ammo is not surprising, to make sure it cycles properly.

There is a more mild spring included for subsonic rounds. Unless you really see a need for using subsonic ammunition, leave the default slide spring installed.

Seating the Magazine
Something I have seen from everyone who has handled the Mosquito: They fail to seat the magazine properly. I tell them to hit it, with a rap. Seat it. Pushing it up does not seat the mag.

Trigger Pull
The trigger is nice and light, set at the factory at about 2 pounds on my model, with no creep.

Accuracy
This weapon is remarkably accurate, giving routine 1.5" groups at 50 feet from a standard rest. There were no failures of any kind in a test run of 500 rounds of CCI Mini-Mag HP ammunition.

I'll keep testing it, but so far I am very pleased with this weapon. The sights are robust, and allow for accuracy, and having no function errors after 500 rounds is a good indicator. Stay tuned...