My Sig Mosquito is a Finicky Eater

revwood · Aug 4, 2015

My Sig Sauer Mosquito (.22LR) jams or misfires almost every time I try to fire it. We're talking an 80 - 90% failure rate!

The gun is so unreliable that it just sits in the safe. The only reason I haven't sold it is that I don't want to pass my problem on to some other unsuspecting soul. I bought the gun used, so I suspect this is what happened to me.

I have tried several different brands of .22LR and it doesn't seem to like any of them. Is it possible that it's the gun and not the ammo? I'm thinking maybe the firing pin isn't hitting the round hard enough or something similar.

The gun only cost around $250. Is it worth having a gunsmith investigate? Anyone have a recommendation on a gunsmith?

MauiWowie · Aug 4, 2015

This is a known problem with the skeeters.
Easy non gunsmith fix is to load mags one round at a time.
Polish the feed ramp.
Lube the snot out of it.

Mine workes like a charm now.

Cut and paste from SigForum:

Advice...make sure there is a thin coat of oil inside the rail grooves on the slide. Make sure you lubricate the extractor through the little hole on the slide (not too much, but a drop will do). Make sure there is a thin coat of oil on the face of the hammer.

These steps ensure all friction areas are properly lubricated. The gun does not like low velocity bargain basement ammo. But, high velocity rounds are perfect.

-Z/28- · Aug 4, 2015

Try CCI minimags. Best .22 ammo for a Mosquito in my experience.

MacGuns · Aug 4, 2015

A steady diet of CCI minimags is all I feed my skeeter. It also likes to run wet.

protegeV · Aug 4, 2015

my ppk/s is the same way. Wont work with anything but minimags

Straightshooter · Aug 4, 2015

Finally fixed mine. Oil it all you want and it will make no difference. The thing is a POS from the factory.

Feed problems can be fixed by grinding a wider, deeper slope on the feed ramp with a dremel. Polish it up real good and that problem will be solved.

The second issue with the Mosquito is the light firing pin strikes. Sometimes you have to pull the hammer back 2 or 3 times to set off a round. This is because the pin is not allowed to go far enough forward because it is being stopped by a cross bar the runs over the top of the bolt. If you grind a notch in the bar where the firing pin hits, it will work like a charm. You can find Ytube videos of this fix.

To remove the bolt from the slide, loosen the rear sight screw which holds a tab on top of the bolt. The bolt will then drop down with a little help. Be careful to note where the springs go. There is also a very, very, very small detent ball and spring in the left thumb lever of the safety. Cover the area with your hand or a cloth when you remove this as you will never find it should it take flight. Hint: This little bastard is a bear to reassemble.

sbmike · Aug 4, 2015

One other thing to consider, which happened to me, is that without knowing it, my right thumb was just barely touching the slide which impeded it just enough for it to fail to eject rounds reliably. I've not experienced the light strikes on mine. Not wanting to tempt fate with known issues, however, I only run CCI MiniMags through it and it has been a fun range gun for a change of pace.

5.56blaster · Aug 4, 2015

Mine does not eject for $hit. I miss my P22.

Straightshooter · Aug 4, 2015

Forgot to mention, I also sharpened the hook on the elector.

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Pinecone · Aug 4, 2015

Lube properly.

Shoot CCI Minimags.

I picked mine up from a MDS member who was frustrated with it. Wear marks indicated a lack of lube. Cleaned, lubed and ran 100 out of 100 Minimags.

Blaster229 · Aug 4, 2015

Most semi auto .22's are a pos anyway.

clandestine · Aug 4, 2015

SIG and Walther .22 pistols are junk IMO. Can't polish a turd.

Straightshooter · Aug 4, 2015

They are my feelings also. The Sig is such a POS that I would not even consider selling it to another unsuspecting fool.

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Naptown34 · Aug 4, 2015

Straightshooter said:
They are my feelings also. The Sig is such a POS that I would not even consider selling it to another unsuspecting fool.

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My sentiment exactly. I wouldn't sell mine to anyone I know.

It's a
POS Jammomatic!!!

Straightshooter · Aug 4, 2015

I wouldn't pawn it off on anybody.

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traveller · Aug 4, 2015

A while ago I wanted a .22 semi, mainly to introduce new shooters. I had my mind on a Mosquito or a Walther P22. My FFL told me that he stocks neither and that he wouldn't sell me a Mosquito and the Walther only if I promise not to bug him if it doesn't work. He pulled a Ruger SR22 from the display case told me 'buy this and you will be happy'. I bought it and I am happy.

DYI01 · Aug 5, 2015

traveller said:
He pulled a Ruger SR22 from the display case told me 'buy this and you will be happy'. I bought it and I am happy.

I agree, I bought an early SR22 Pistol and it's been flawless. I easily have over 10k rounds of federal and winchester bulk pack through it. The only time I have issues with it, is when it's extremely dirty I get an occasional failure to feed.

Maverick0313 · Aug 5, 2015

My SIG Mosquito was a pain in the ass. Sold it. Got an SR22. NEVER LOOKED BACK.

Squaregrouper · Aug 5, 2015

Browning Buckmark
/thread

NateIU10 · Aug 5, 2015

The PPQ 22 is also fantastic in my opinion. Ran off our mixed bag of crap 22 no problem.

My Sig Mosquito is a Finicky Eater

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