Sig Mosquito

[Dirtlaw]

Some range time with fellow Cal-gunner 50-yarder and my wife today. Lots of fun, but I'm having a problem with my Sig Mosquito. We think it's an issue with the magazine. Perhaps a weak spring. Perhaps a sticking plunger. Failure to properly load (bullet stuck at an angle without entering chamber) and sometimes failure to eject. The round apparently has to jump over the feed ramp. Has anyone on the board had similar problems? What solution(s) worked for you? I'm trying to get as much information as possible before I start attempting fixes.

[TNT8284]

My father has a Sig Mosquito and we have had quite similar experience that you had. Just to ask, was your firearm lubed and oiled before the range?
My father and I both found that the Mosquito ran much better wet rather than dry, but we still experienced FTF and FTE even drenched.

[Wordupmybrotha]

Mosquito is problematico.

[pythonfan]

Cci mini mag 40gr round nose in a clean wet mosquitio.

[Barang]

my wife used to have one. she got bored with .22 fast so she sold it.
make sure to drop oil in that small hole.
use the high velocity recoil spring.
use cci mini-mag, winchester super x or remington golden bullet.

[Strykeback]

My wife handled that sig but upon research it was found very problematic and ammo sensitive. I got a browning stainless target buckmark with 4 mags and my wife will shoot that thing until we run out of all the boxes of 22 that I brought.

Sent from my SM-N960U using Tapatalk

[cabikefreak]

What pythonfan said. I got one cheap from a buddy and made a mission to fix it up. I got mine running with other ammo usually, but only on CCI minimags are 100% (or very close to it). If you want to improve it, do your research.

[Dirtlaw]

My father has a Sig Mosquito and we have had quite similar experience that you had. Just to ask, was your firearm lubed and oiled before the range?
My father and I both found that the Mosquito ran much better wet rather than dry, but we still experienced FTF and FTE even drenched.

Heavily lubed was my first thought too. So it was wet at the time. We used a variety of rounds but mostly Aguila (not sure of spelling) high velocity. Next time I'll bring mini mags to see how they perform. Some time ago I did a little research into which round had the highest velocity. Unfortunately I mislaid the conclusions so I just grabbed the first high velocity that came into sight and that was the Aguila.



We did notice that the GSGa 922 CA, which I also brought and which performed flawlessly, had a ramp that was deeply grooved and a round in the magazine seemed more aligned with the chamber than the Sig. The round in the Sig seemed to almost jump over the ramp when it cycled correctly. So, I will probably start by polishing the Sig ramp. We also noticed that the Sig magazine had a pretty weak spring and some of the machining on the magazine had sharp edges that could be restricting free movement of the round pusher. I can bevel the edges easily, but exchanging the spring for a more powerful one might be a challenge. Changing the recoil spring is also a possibility, but that too will be more challenging than the easy fixes which I want to try first.

[jarhead714]

My advice to improve the Mosquito is to sell it for less than what you paid and then buy a Ruger SR22 for more than what you should pay.

[DB>]

Yup - SR22 runs like a champ...

Based on your descriptions, polish the feed ramp, clean the chamber. I recently ran into some 22wmr Aguila that was slightly oversize and wouldn't seat properly when feeding and ALSO not eject because the extractor couldn't reliably yank the spent casing out. Had to aggressively clean the chamber and polish until they slip in (and out, with extractor) and seat as they are supposed to. CCI and Hornady were better, but still had eject/extract issues until I cleaned everything up.

Seen other .22lr pistols have similar problems with Golden Bullets having varying diameters, and jamming.

Disassemble and clean the mags, dirty mags can cause rounds not to present properly.

.22's tend to get "dirty", so a field strip and thorough cleaning couldn't hurt - I've switched to Slip2000 - supposed to lube things up without having to run wet.

Keep in mind you could have MULTIPLE things going on, and you may have to carefully experiment with dummy rounds/spent casings and possibly live ammo as you diagnose the problems.

.22lr pistols tend to be finicky in general (other than that SR22, and the cheap Phoenix HP22A), and can be a pain to get running well.

[Fishslayer]

Is the barrel screw tight?

[Dirtlaw]

Is the barrel screw tight?

The barrel did not seem loose, but I will check that out. One downside of rim fire is that the snap caps get chewed up so quickly, so testing without live ammo is a bit of a hassle. Still there is something particularly relaxing about the 22. Something about the round makes me feel like a kid again.

[DB>]

Use the dummy loads to check alignment of the mag/slide/barrel, not to "dry fire" - you just want to check the cycling with the dummy round passing slowly through the parts to see if there are any hangups.

You're manually manipulating the components to see if anything isn't smooth - it should be more obvious if there's an issue, since you're not relying on the mini explosion to move things around (recoil spring or complete assembly optional)

That should help your dummy rounds last longer too <wink>.

Once you've ironed out any burrs, snags, etc., you can put it back together, and use the dummy rounds to test cycling manually - if it's all good, then a range trip can confirm live fire functionality.

22 semi-autos can be ammo picky and that takes live firing to diagnose and confirm it's resolved (which may or not ultimately end up being possible on some pistols). It can be VERY frustrating, but it's also a good learning experience as you try to find the things that need to be fluffed/buffed/polished/filed or whatever. Then again, the satisfaction if you get it running well is a great feeling!

[oddball]

Mosquito is problematico.

Yeah, it was tempting to buy one back in the day, hey, it's a Sig, right? But soooo many problems. It kinda just faded off into the sunset without fanfare...

[A-J]

The mosquito likes to be well lubed and have good high velocity ammo. Bear in mind that HV ammo is not the same between manufacturers.

Remington Golden bullet 40gr High Velocity is rated at 1255 FPS
CCI Stinger High velocity is rated at 1640

I've never had an issue with anything rated at 1400 FPS and I've put a couple thousand rounds through mine now.

Sadly, my brother's Walther will eat any rounds he puts in it and fire every time. His gun was less expensive too. Dammit!